LIBRARY OF CONGRESS. 



Shelf .aB.5L* 5" 



UNITED STATES OF AMEKICA. 



^ 




Fig. 1. — The Skeleton. 

THE OUTER LINES SHOW THE FORM OF THE HUMAN BODY WHEN TH1 
IS CLOTHED WITH FLESH. 



SKELETON 



AN 



ACADEMIC PHYSIOLOGY 



AND 



HYGIENE. 



EMBRACING SPECIAL CHAPTERS ON FOODS AND THEIR PREPARA 
TION; WATER AND OTHER BEVERAGES; AIR AND VENTILA- 
TION; THE REMOVAL OF WASTE MATTERS; EXERCISE, 
REST, AND RECREATION ; BATHING AND CLOTH- 
ING; HYGIENE OF THE SPECIAL SENSES, 
AND THE EFFECTS OF STIMU- 
LANTS AND NARCOTICS ON 
THE HUMAN SYSTEM. 



y 

BY ., ,,- 

ir 

ORESTES M. BRANDS, 

LATE SUPERINTENDENT OF SCHOOLS, PATERSON, N.J. 
AUTHOR OF " LESSONS ON THE HUMAN BODY," " HEALTH LESSONS FOR BEGINNERS, 
AND "GOOD HEALTH FOR CHILDREN." 



AND 



HENRY C. VAN GIESON, A.M., M.D., 

GRADUATE OF THE COLLEGE OF PHYSICIANS AND SURGEONS, NEW YORK. 




p3 Ty 



LEACH, SHEWELL, AND SANBORN, 

BOSTON AND NEW YORK. 






^ 



Copyright, 1893, 
By Orestes M. Brands. 



Type Setting and Electrotyping by 
C. J. Peters & Son. 



Presswork by Berwick & Smith. 



PREFACE 



In the preparation of this volume an endeavor has been 
made to keep steadily in view the fact that the study of 
the structure and functions of the body and of its various 
organs should conduce to an intelligent conception of the 
normal conditions and processes through which health and 
life are maintained. Anatomy and Physiology, while not 
being unnecessarily neglected, have been treated as a 
means rather than as an end. 

In early eras of thought, bodily disorder and disease were 
regarded as the gifts of the gods, and as marking their 
judgments ; and the task of preventing plagues, fevers, and 
the mysterious diseases of brain and mind, was esteemed as 
hopeless and impracticable. But in course of time the 
lessons taught by bitter experience and the progress -of 
modern civilization Began to exercise a distinct influence 
upon public health. The knowledge possessed by the 
few was sought by the many ; and the domains of the theo- 
logian and the scientist began to be invaded in the search 
for light on all subjects pertaining to moral, mental, and 
physical well-being. The sources and causes of disease 
began to be tolerably well understood, and it became 
known that man possesses the power of preventing many 
of the ailments which shorten life and decimate the popu- 
lation of communities and nations. 



VI PREFACE. 

Hygiene founds its lessons to the individual upon the 
same basis as those which it inculcates on the masses. 
There are so many conditions over which an individual has 
control, that it is impossible to determine which is abso- 
lutely of the greatest importance. It may be safely said 
that one must first possess the intelligent conception of the 
normal conditions of structures and processes to which we 
have referred, and then must become acquainted with the 
nature, quantity, and proper preparation of foods, and 
the conditions essential to their healthy digestion ; the com- 
position of the beverages which he imbibes, their values, 
and their effects on the organism ; the composition of air, 
the causes affecting its purity, and the means of securing its 
change and renewal when vitiated; the relations of proper 
bathing, cleanliness, and clothing to health must be under- 
stood ; the part played by exercise, rest, and recreation in 
maintaining physical and mental vigor must be known ; the 
dangers attending the accumulation of refuse matters in 
the vicinity of human habitations must be appreciated, and 
the means of effectively disposing of them should be 
known ; and finally, the individual should acquire knowl- 
edge that will enable him to render intelligent assistance, 
and often save life, in emergencies. The development of 
public interest in all matters relating to sanitary science 
renders needless an apology for adding special chapters on 
the foregoing topics. 

While the treatment of each topic is elementary, and 
divested of technicality as far as practicable, the essential 
facts are stated with the fulness needed to set forth 
clearly their educational value. The authors have brought 
to bear special knowledge of the subjects on which they 
have written, together with practical experience in teach- 



PREFACE. Vll 

ing them. In addition, the standard works of Dalton, Car- 
penter, Huxley, the manuals of health-science of Wilson, the 
American Health Manuals, etc., and the writings of many 
other eminent scientists, have been consulted, and most 
valuable assistance derived from their teachings. 

In conclusion, the authors trust that this volume will 
possess attractions, and attain a popularity and usefulness, 
equal to those of the other works of the series which it is 
intended to complete and crown. 

O. M. B. 
H. C. V. G. 
February, 1893. 



CONTENTS. 



CHAPTER PAGE 

I. — Introductory. — Knowledge of the Body. — Divisions of the 
Subject. — Anatomy, Physiology, and Hygiene and their Re- 
lations. — Composition of the Body. — Cell Structure. — The 
Tissues. — The Fluids. — Organs and Systems. — Public Hygi- 
ene and Personal Hygiene ....... I 

THE OSSEOUS SYSTEM, OR SKELETON. 

II. — Composition and Structure of Bone. — Composition of 
Bone. — Structure of Bone. — The Cartilages. — Classes of 
Bones. — Growth and Development. — Repair when Frac- 
tured II 

III. — The Skeleton. — The Skeleton and Its Functions. — The 
Head and Its Structure. — Bones of the Skull and Face. — 
The Teeth 15 

IV. — The Skeleton (continued). — The Trunk and its Structure 
and Functions. — The Upper Extremities: their Structure and 
Functions. — The Hand and Its Mechanism, etc. . . .20 

V. — The Skeleton (concluded). — Hygiene of the Bones. 
— The Lower Extremities : their Bones, Joints, and Func- 
tions. — Classes of Joints in the Skeleton. — Ligamentary 
Structure. — The Coverings of the Skeleton. — Hygiene of 
the Bones. — Primary Requisites. — Distortion from Faulty 
Positions. — Distortion from Improper Dress. — Diseases of 
the Bones. — Sprains, Dislocations, Fractures. — Care of the 
Teeth 30 



CONTENTS. 



THE MUSCULAR SYSTEM. 

CHAPTER PAGE 

VI. — The Muscles. — Structure, Functions, Classes. — Muscle 
and Its Functions. — Structure of Muscle. — Size, Form, 
and Attachments. — Antagonists. — Tendons and Ligaments. 

— Circular Muscles. — Muscles of Expression. — Muscles of 
the Skin. — Contractility of Muscle. — Velocity of Contrac- 
tion. — Muscular Sense. — Irritability of Muscle. — Un- 
striated Muscle. — Arrangement of Fat . . . -47 

VII. — Brief Description of Important Muscles. — Muscles of 
the Head and Face. — Muscles of the Neck. — Muscles of the 
Trunk. — Intercostals and Diaphragm. — Muscles of the 
Upper Extremities. — Biceps, Triceps, etc. — Muscles of 
the Lower Extremities. — Flexors and Extensors. — Muscles 
attached to Levers 53 

VIII. — Physiology and Hygiene of Muscular Exercise. — Object 
of Exercise. — Influence of Exercise. — Muscular Strength. 

— Amount of Exercise. — Proper and Improper Exercise. — 
Preternatural Muscular Development. — Modes of Exercise. 

— Artificial Props. — Tight Clothing. — Effects of Alcohol 
and Tobacco ......... 62 



THE BLOOD AND ITS CIRCULATION. 

IX. — The Blood: Its Composition, Properties, etc. — The 
Vital Fluid. — Properties of Blood. — Coagulability. — The 
Red Corpuscles. — The White Corpuscles. — Quantity of 
Blood. — Quality of the Blood. — The Lymph . . -75 

X. — The Circulation. — The Circulatory Apparatus. — The Heart. 

— Muscular Structure of the Heart. — Cavities, Valves, 
etc., of the Heart. — Course of the Blood in the Circulation. 

— Action of the Heart. — Sounds of the Heart. — Cardiac 
Impulses. — Causes Influencing the Heart-beat. — The Nerve 
Force of the Heart ........ 80 

XI. — The Circulation {continued). — The Arterial System. — 
Structure of the Arteries. — The Capillaries. — The Veins. 

— Vaso-motor Nerves. — Animal Temperature . . . 91 



CONTENTS. XI 

CHAPTER PAGE 

XII. — Hygiene of the Blood and Circulation. — Quality and 
Quantity to be Maintained. — Effects of Pressure upon the 
Veins. — Proper Distribution of the Blood. — The Heart 
and Mental Excitement. — Effects of Alcohol on the Blood. 
— Effects of Alcohol on the Heart and Other Blood- 
vessels .......... ioo 



THE RESPIRATORY, OR BREATHING SYSTEM. 

XIII.— The Respiratory Organs. — Why We Breathe. —The 
Organs of Respiration : Larynx, Trachea, Bronchi, Lungs, 
etc. — Action of Respiration; or, How We Breathe. — Tidal, 
Supplemental, and Complemental Air. — Difference between 
Inspired and Expired Air. — Rapidity and Amount of 
Respiration. — Diaphragmatic and Costal Breathing — Res- 
piratory Sounds or Murmurs. — Respiration Influenced by 
Atmospheric Pressure ........ 107 

XIV. — The Air We Breathe. — The Atmosphere. — The Accidental 

Components of Air. — Dust. — Bacilli. .... 122 

XV. — Ventilation and the Removal of Waste Matters. — 
Object of Ventilation. — Ventilation Ignored in the Construc- 
tion of Dwellings. — Principles and Means of Ventilation. 

— Natural Agents of Ventilation. — Methods of Ventilation. 

— Artificial Ventilation. — Removal of Refuse Matters. — 
Cesspools. — Sewers. — Effects of Alcohol and To- 
bacco . .......... 128 



NUTRITION AND DIGESTION. 

XVI. — Nutrition. — Necessity of Food. — Hunger and Thirst. — 
Classes of Food-stuffs. — Proteids, or Nitrogenous Foods. 

— Fats or Oils. — The Amyloids or Starches. — Mineral 
Salts. — Necessity for a Mixed Diet. — Proportion of Food. 

— Elements and Quantity of Food 143 

XVII. — Values of Articles of Food. — Vegetable Foods. — Garden 

Produce. — Fruits. — Confectionery 152 



Xll CONTENTS. 

CHAPTER PAGE 

XVIII. — Values of Articles of Food {concluded). — Animal Foods. 

— Circumstances Affecting the Value of Animal Food. — 
Meats which should not be Eaten. — Special Properties of 
Meats in Common Use. — Milk: Its Value, Dangers, and 
Adulteration. — Butter and Cheese. — Eggs. — Cooking. 

— Cooking of Meat. — Cooking of Vegetables. — The 
"Mixing " of Bread. — Baking of Bread. — Condiments . 158 

XIX. — Drinks. — Water and Health. — Physiological Offices of 
Water. — Rain Water. — River and Surface Water. — 
Spring Water. — Well Water. — Hardness of Water. — 
Action of Water upon Lead. — Means of Purifying Water 

— Water Examined by the Senses. — Temperature of 
Water-supply ........ 



XX. — Drinks {concluded). — Narcotics and Stimulants. — Ar 
tificial Drinks. — Tea. — Coffee. — Cocoa. — Adultera 
tions of Tea, Coffee, and Cocoa. — Alcoholic Beverages 
— Alcohol and Its Properties. — Alcohol as a Beverage 
and as a Poison ....... 



174 



184 



XXI. — Digestion. — Mastication, Insalivation, and Degluti- 
tion. — Digestion Defined. — Organs and Processes of 
Digestion. — Mastication. — Insalivation. — The Salivary 
Glands and their Action. — Nature and Action of Saliva. 
— Effects of Tobacco on Salivary Digestion — Action of 
Acids on Salivary Digestion. — Deglutition . . .193 

XXII. — Digestion {continued). — Chymification, or Stomach 
Digestion. — The Stomach. — The Gastric Juice. — 
Stomach or Gastric Digestion. — Absorption from the 
Stomach. — Time required for Gastric Digestion. — Alcohol 
and the Stomach. — Alcohol, Digestion, and the Gastric 
Juice. — Alcohol and Thirst. — Alcohol and the Produc- 
tion of Fat. — Effects of Tobacco on Digestion 



XXIII. — Digestion (concluded). — Chylification, or Intestinal 
Digestion. — Difficulty of Investigation. — The Intestines 
— The Small Intestine. — The Large Intestine. — The In 
terior of the Intestines. — Lacteals. — Intestinal Glands. — 
The Liver. — The Pancreas. — The Spleen. — Chylifica 
tion. — Absorption of the Chyle. — Evils of Constipation 



203 



216 



CONTENTS. Xlll 



THE NERVOUS SYSTEM. 

CHAPTER * PAGE 

XXIV. — The Nervous System. — The Brain. — Functions of the 
Nervous System. — Divisions of the Nervous System. — 
Nervous Tissue. — The Brain. — The Cerebrum. — The 
Cerebellum. — The Pons Varolii. — The Medulla Ob- 
longata .......... 232 

XXV. — The Spinal Cord. — The Nerves. — The Spinal Cord 
and Its Functions. — Reflex Actions. — The Nerves in 
General. — Sensory and Motor Nerves. — Cranial and 
Spinal Nerves and their Functions. — The Sympathetic 
Nervous System. — Nervous Impulses. — The Mind . 241 

XXVI. — The Essentials of Healthy Nervous Action. — Pri- 
mary Requisites. — Mental Work. — Rest and Sleep. — 
Insomnia. — Pure Air. — Clothing. — Amount of Sleep 
Requisite. — Narcotic Sleep. — Rest in Exercise and Other 
Recreation. — Heredity. — Alcoholic Drinks as related to 
Nervous Disease and Insanity. — Baneful Effects of 
Opium, Morphia, Chloral, Tobacco, etc. — The Use of 
Alcohol as related to Crime 253 



THE SKIN, CLOTHING, AND BATHING. 

XXVII. — Structure and Functions of the Skin. — General Im- 
portance of the Skin. — The Layers of the Skin, etc. — 
The Derma, or True-skin. — The Epidermis, or Scarf- 
skin. — Muscles of the Skin ...... 271 

XXVIII. — Structure and Functions of the Skin {concluded). — 
Vessels, Glands, and Nerves. — Capillaries. — Special 
Nerves. — Sebaceous Glands. — Sweat Glands. — Forms 
and Quantity of Perspiration. — Absorption through the 
Skin. — Respiration through the Skin. — Functions of 
the Skin, Lungs, and Kidneys Compared . . . 276 

XXIX. — Regulative Agency of Perspiration. — Perspiration and 
Heat. — Perspiration and Cold. — Perspiration and Moist 
Air. — Perspiration and Dry Air. — The Hair. — The 
Nails 283 



XIV CONTENTS. 

CHAPTER PAGE 

XXX. — Care of the Skin. — Bathing. — Hygiene of the Skin. 

— Cleansing Necessary. — A Warm Bath for Cleanliness: 
Time, Mode, and Frequency. — Hot Baths in Cases of 
"Colds." — Cold Baths and their Regulation. — Sea- 
Bathing. — Friction Baths. — Washing of Face and 
Hands. — Cosmetics. — Care of the Scalp. — Hair Dyes. 

— Effects of Alcoholic Drink on the Skin and Bodily 
Temperature. — Tobacco and the Skin. — Chronic Diseases 

of the Skin .288 

XXXI. — Clothing. — Object of Clothing. — .Essentials in Clothing- 
material. — Properties of Woollen Clothing. — Silk, Cot- 
ton, and Linen as Clothing. — India-rubber and Water- 
proof Clothing. — Influence of Color in Clothing. — 
Common Errors in Dress. — Cleanliness and Care of 
Clothing. — Poisonous Clothing ..... 298 

THE SPECIAL SENSES. 

XXXII. — Sight. — Sensation in General. — Special Sensations. — 
The Sense of Sight. — Anatomy of the Eye in General. 

— Coats, Humors, Lens, etc. — Appendages of the Eye. 

— The Phenomena of Sight. — Visual Sensation; or, 
How We See. — Normal Sight, Near-sight, and Far-sight. 

— Recognition of Color, and Color Blindness. — Visual 
Judgments. — Optical Delusions . . . . -314 

XXXIII. — Hygiene of the Eye and Care of Eyesight. — Essen- 

tials of Perfect Sight. — Rules for the Care of the Eyes. 

— Defects of Sight requiring Spectacles .... 330 

XXXIV. — Hearing. — The External and the Middle Ear. — 

Location of the Ear, etc. — Divisions of the External Ear. 

— The Auricle. — The Auditory Canal. — The Tympanic 
Membrane or Drum-head. — Divisions of the Middle Ear. 
— The Tympanum or Drum. — The Eustachian Tube. — 
The Mastoid Cells 336 

XXXV. — Hearing {continued}. — The Internal Ear. — Divisions 
of the Internal Ear. — The Vestibule. — The Cochlea. — 
Semicircular Canals. — Sound and Its Nature. — How 
We Hear 343 



CONTENTS. XV 

CHAPTER PAGE 

XXXVI. — Hygiene of the Ear, and Care of Hearing. — Care of 
the Auricle. — Care of the Auditory Canal. — Removal 
of Foreign Bodies. — Care of the Drum-head. — Of the 
Eustachian Tube. — Effects of Alcoholic Drinks and 
Tobacco on the Hearing 347 

XXXVII. — Taste and Smell. — Taste and Smell Compared. — The 
Organs of Taste and their Structure. — Curiosities of the 
Taste. — How We Taste. — The Sense of Smell, and Its 
Importance. — The Organ of Smell, and Its Structure. — 
Curiosities of the Sense of Smell ..... 352 

XXXVIII. — Touch. — Touch as a Sensation. — The Organ of Touch 
and Its Structure. — Curiosities of Touch. — Sensations 
of Contact and of Temperature. — Delicacy of Touch. — 
Effects of Stimulants and Narcotics on Special Senses . 359 

XXXIX. — Emergencies; or, First Aid to the Injured. — Poisons 
and Their Antidotes. — Drowning. — Sunstroke and 
Heat-Exhaustion. — Bleeding from Wounds. — Burns 
and Scalds. — Foreign Body in Throat. — Clothing 
Ablaze. — Fainting. — Disinfectants .... 371 

INDEX 381 



ACADEMIC PHYSIOLOGY 



CHAPTER I. 

INTRODUCTORY. 



1. Knowledge of the Body. — The investigations and ex- 
periments made by some of the most profound thinkers 
of all countries and ages have been employed in the dis- 
covery of the structure and functions of the human body. 
This continued study and research has not been inspired 
by mere idle curiosity and for its gratification. The pres- 
ervation of health, and the desire for long life, as a 
sequence, have stimulated inquiry into all that continued 
to remain unknown of the structure of the body, of the 
offices and actions of its various organs, of the relations 
of each organ and set of organs to all others, and of the 
conditions necessary to the healthy and harmonious activ- 
ity of the whole organism. 

2. Having a knowledge of only the general outlines of 
the structure of the body and of its various functions, all 
can understand important hygienic laws, the proper ob- 
servance of which tends to insure health, long life, and 
happiness. It is of but little use to know how our bodies 
are constructed and what functions are performed by their 

i 



2 ACADEMIC PHYSIOLOGY. 

organs, unless we utilize such knowledge in the preven- 
tion of disease and the preservation of life. When we 
know just what results will follow the violation of each 
law of existence, we become measurably the arbiters of 
our own health ; and our enlightened judgment stands as 
a guard over our lives, possibly preventing the first step 
toward disease. 

3. Divisions of the Subject of Study. — The sciences which 
treat of the structure, functions, and preservation of health 
of the body, are Anatomy, Physiology, and Hygiene. 

4. Anatomy (Gr. ana, up ; and temnein, to cut) is the 
science which describes the structure, situation, and rela- 
tion of the different parts of the body. A knowledge of 
this comes only from a minute examination of all the 
parts that constitute the structure, and has been obtained 
through microscopic examinations and by dissections of 
lifeless bodies. 

5. Through continued investigation and experiment the 
amount of knowledge has been enormously increased, and 
that which was already possessed has been rendered much 
more accurate. Surgical skill has kept pace with this prog- 
ress in many directions previously unthought of. Oper- 
ations that were formerly regarded as quite certainly fatal 
to life, are now relieved, to a great extent, of their dangers 
and terrors. The steady, onward progress of scientific 
knowledge enables the surgeon to relieve diseased condi- 
tions by means of operations that would, in former times, 
have been ascribed to the agency of the " black art." 

6. Physiology (Gr. phnsis, nature, and logos, discourse) 
is the science which describes the functions of organs 
and sets of organs, or the mode in which they operate. 
Physiological knowledge comes, in part, from experiment 



INTRODUCTORY. 3 

and the study of structures, and largely from experience 
and observation. Experiments made upon the lower 
animals have added greatly to our knowledge of physio- 
logical processes. 

7. According as it treats of one or other of the two 
great groups of organic beings, it is either animal physi- 
ology, or vegetable physiology. Human physiology is, of 
course, restricted to the human body. 

8. Hygiene (Gr. hygeia, health) is the science, practical 
hygiene the art, of preserving health. While it is the 
province of medical science to treat disease when it act- 
ually appears, it is that of hygiene to enable us so to place 
ourselves in relation to our surroundings, and so to regu- 
late our lives, that disease may be warded off. Medicine 
deals with cure, hygiene with prevention ; and prevention 
is better than cure. 

9. The science of health preservation is wide in its 
scope, embracing as it does inquiries into nearly all other 
sciences. It calls upon chemistry to contribute informa- 
tion concerning the composition of foods, the nature of the 
impurities of air, and the contaminations of water-supply. 
It appeals to physics to explain the diffusion of gases, — 
how noxious gases from sewers gain access to our dwell- 
ings, and calls upon it for contrivances to abate the evil ; 
again it calls upon this science to explain methods of secur- 
ing proper ventilation of our abodes. It demands of botany 
and zoology descriptions of the minute parasites that 
sometimes infest foods and render them unwholesome. 
Of geology it inquires the nature of the strata from which 
supplies of water are obtained ; and from physiology it 
learns the conditions which should prevail in healthy 
action of the body. 



4 ACADEMIC PHYSIOLOGY. 

10. Composition of the Body. — There are sixty-four sub- 
stances which are known as simple substances, or ele- 
ments ; and they are so regarded because they cannot be 
decomposed and resolved into simpler constituents. All 
animal, vegetable, and mineral bodies are formed by a 
union of various numbers of these elementary substances 
in different proportions and ways. 

11. Chemistry has demonstrated that the human body 
contains fourteen elementary substances, viz., oxygen, 
hydrogen, nitrogen, carbon, phosphorus, calcium, fluorine, 
sulphur, chlorine, sodium, iron, potassium, magnesium, and 
silicon. In the bodily structures these elements do not 
exist in simple form, but are so combined as to form chem- 
ical compounds called proximate principles. 

12. The proximate principles, or compound substances 
constituting the body, are of three classes, viz., those 
derived from the mineral or inorganic world, as water, 
chloride of lime, phosphate of lime, phosphate of soda, 
chloride of sodium (common salt), and other salts ; the 
carbonaceous compounds, as starches, sugars, and oils ; and 
the nitrogenous compounds, as albumen, fibrine, etc. 
These exist in a healthy human body weighing 154 pounds 
in about the following proportions : Water, a compound 
of oxygen and hydrogen, 1 1 1 lbs. ; gelatine, composed of 
carbon, hydrogen, oxygen, and sulphur, 15 lbs. \fat, 12 lbs. ; 
phosphate of lime, forming the principal part of the 
earthy matter of the bones, 5 lbs. 13 oz. ; carbonate of lime, 
also entering into the composition of bone, 1 lb. ; albumen, 
found in the blood, brain, and almost all the other organs, 
4 lbs. 3 oz. ; fibrine, forming the clot of the blood, and 
found in the muscles, about 4J lbs. ; calcium found in the 
bones, 3 oz. ; phosphate of soda, found in the brain and all 



INTRODUCTORY. 5 

other nervous tissue, 400 grs. ; phosphate of potash, also 
found in the brain and nerves, 100 grs. ; phosphate of mag- 
nesia, found in the bones, 75 grs. ; chloride of sodium, 376 
grs. ; sulphate of soda, found in the blood, more than 1 oz. ; 
carbonate of soda, in the blood and bones, about 1 oz. ; 
sulphate of potash, about 1 oz. ; peroxide of iron, in the 
blood and elsewhere, more than 9 oz. ; and silica, a very 
small quantity. 

13. These substances and their proportions are not given 
here as necessary for memorization, but in order that the 
diversified nature of the composition of the body may be 
impressed. They are constantly undergoing change, being 
transformed into waste or effete products, which are dis- 
charged from the body. This change is necessary to life ; 
and in order to compensate for the waste occasioned by 
this constant destruction, new material must be regularly 
supplied. All the elements necessary for the maintenance 
of the composition of the body are derived from proper 
food, and are held in solution in the blood which distrib- 
utes them to the various structures. 

14. Food is taken into the body in obedience to a want 
made known by the sensation of hunger when it relates to 
solid or semi-solid matters, and by thirst when the want 
relates to water. 

15. Cell Structure. — The microscope shows that animal 
as well as vegetable structures are composed of cells (Lat. 
cella, a store-room). A cell is a minute, membranous sac 
enclosing a more or less fluid mass of matter. In this sub- 
stance, in most cells, are found one or more spots or nod- 
ules of condensed matter called nuclei (Lat. nucleus, a nut 
or kernel). These nuclei first exist in a transparent, struc- 
tureless mass called protoplasm. 



6 ACADEMIC PHYSIOLOGY. 

In the course of development, this matter breaks up into 
microscopic globules, each enclosing a nucleus ; and thus 
the cells are formed and multiply. 

16. The Tissues of the Body. — The word tissue means, lit- 
erally, a woven structure. Variously modified in form and 
nature, the interwoven, grouped, or united cells form 
different tissues or solid portions of the body. 

17. The tissues have been classified and named as fol- 
lows : Epithelial tissue includes the skin and delicate 
lining membranes of the cavities of the body, the hair, and 
the nails of the fingers and toes ; muscular tissue, the con- 
tractile tissue of which all the muscles are examples; 
adipose tissue, composed of fat cells and enclosed, fat ; 
cartilaginous tissue, commonly called " gristle," forms the 
surfaces of joints and the elastic frames of soft parts, such 
as the outer ear, the nose, etc., and constitutes the tendons 
of muscles ; nervous tissue constitutes the substance of the 
brain and nerves ; connective tissue is the delicate, mem- 
branous sheet which invests muscles and all the organs of 
the body, holding them in place, and separating parts from 
adjacent ones. Its chief use is that of support. Osseous 
tissue comprises the bones and the teeth. 

18. The Fluids of the Body. — The blood is the most abun- 
dant fluid of the body, being estimated at about one-eighth 
of its weight. Beside the blood there are the fluids enclosed 
in the eyeballs, the tears, the saliva, the bile, the intestinal 
juices, the synovial fluid of the joints, etc., all of which 
will be more particularly noticed later. 

19. Organs and Systems. — Any definite part of the body 
that has a special office or function to perform is called an 
organ (Lat. orga?tum). Thus the heart is the principal 
organ for the propulsion of the blood ; the lungs the prin- 



INTRODUCTORY. 



ciple organs of the breath ; and still more familiar, the eyes 
are the organs of sight, and the ears of hearing. 

20. A number of intimately related organs engaged in 
the performance of the same general function constitute a 
system. Each set of organs is so arranged as to perform 
special offices of its own while acting in harmony with all 
others. Thus we have the osseous system, consisting of the 
bones, which gives support, protection to others, and sup- 
plies levers for the muscles ; the muscular system, com- 
posed of the muscles, supplies the means of motion to the 
body as a whole, and to each of its various organs ; the 
digestive system, comprising several organs, converts food 
into material for the nutrition of the whole body ; the 
circulatory system, composed of the heart, arteries, veins, 
etc., is employed in circulating the blood, thereby carrying 
nutrition to the various parts of the body ; the respiratory 
system comprising the lungs, air-passages, and certain 
muscles, etc., is employed in supplying oxygen and purify- 
ing the blood ; the nervous system, consisting of the brain 
and nerves, presides over all motion and sensation ; the 
organs of excretion, such as the kidneys, sweat-glands of the 
skin, etc., remove the effete material that can no longer be 
used in the body. In addition to these systems of organs, 
we have the separate organs of the special senses, the eye, 
ear, nose, tongue, and skin, by means of which we enjoy 
relations with objects in the world about us. 

21. Public Hygiene ; Personal Hygiene. — Hygiene takes cog- 
nizance of every cause and condition which contributes to 
the maintenance of health and the prevention of disease. 
Owing to the absolute necessities where mankind is con- 
gregated in large numbers, as in towns and cities, every 
civilized nation or community enacts laws which deal with 



8 ACADEMIC PHYSIOLOGY. 

questions of health and the prevention of the spread of 
disease. Sanitary regulations prescribe the conditions 
of abodes and their surroundings, as the carelessness or 
ignorance of an individual is liable at any moment to en- 
danger the safety of his fellows. The removal of nox- 
ious refuse matter, the preservation of the purity of air 
and water supply, the wholesomeness of articles of food 
offered for sale, etc., receive more or less attention through 
legislative enactment. The isolation of persons sick with 
dangerous contagious disease, and the disinfection of 
clothing, utensils, and apartments to destroy the germs 
of disease, receive the supervision of public authority. 
By such means are prevented many of the ailments which 
shorten life and decimate the population. 

22. But the intelligent culture of health by the individual 
far exceeds in power and effectiveness the mandates of 
nations, states, and cities in regard to health. It is through 
the acquisition of health-knowledge and the observance of 
personal hygiene by individuals that good health and pro- 
longed life are to be attained. Disease and suffering are 
largely the results of ignorance. The lessons taught by 
the science of health to the individual are essentially 
those which form the basis of the compulsory health 
enactments of civil government. Every individual should 
become acquainted with the nature of foods, and the quan- 
tity necessary under varying circumstances ; the proper 
preparation of food, and the conditions required for its 
complete digestion. He should understand the properties 
and effects of the beverages which he imbibes. The com- 
position of air, the sources of its impurities, its effects 
when impure, the means for the expulsion of effete air 
and its replacement by that which is pure, should be 



POINTS SUGGESTING QUESTIONS. 9 

known. The relations of exercise, rest, sleep, cleanliness, 
and clothing to health should be understood. The hygiene 
of sight, hearing, etc., should be familar knowledge. 
Finally, every individual should acquire knowledge which 
will enable him to render aid in emergencies and in the 
absence of the physician or surgeon. 

" Nature does require 
Her time of preservation, which, perforce, 
I, her frail son, amongst my brethren mortal 
Must give my attention to." 

Shakspeare. 



Points Suggesting Questions. 

{Note. — It is desirable that questions should be given in such an order as 
to form a systematic and progressive development of the subject, and so 
varied as to cause the same facts to be viewed in different aspects and rela- 
tions and to require a different form of language in the answer. Hence it is 
that good teachers do not allow themselves to be fettered with the set ques- 
tions of a text-book, however good they may be in themselves. Instead of 
formal questions, therefore, a series of suggestive points or heads for ques- 
tions is appended to each prominent division of the text.) 

I. Object of experiment and investigation; what stimulates inquiry. 

2. Utilizing knowledge of structure and function; arbiters of our own health. 

3. The subjects of study. 4. Anatomy defined; the microscope and dissec- 
tion. 5. Increased knowledge and accuracy; surgical skill, operations. 
6. Physiology defined; experiments on animals. 7. Animal and vegetable 
physiology. 8. Hygiene defined; medicine and hygiene contrasted. 9. 
Scope of health science; tributary sciences. 10. Simple substances or ele- 
ments. 11. Composition of the body; proximate principles. 12. Classes of 
proximate principles in body, 13. Constant change and renewal; elements 
in food; distribution by blood. 14. Hunger and thirst. 15. Cell structure; 
a cell; nuclei; protoplasm; multiplying of cells. 16. Tissue. 17. Classes 
of bodily tissue, peculiarities. 18. Fluids, quantity, location. 19. An 



10 ACADEMIC PHYSIOLOGY. 

organ; a system. 20. The various systems and their functions. 21. Cogni- 
zance by hygiene of causes, etc.; necessities where mankind is congregated; 
sanitary regulations; ignorance of the individual, danger. 22. Indvidual 
culture of health important; disease and ignorance; knowledge required 
by the individual, special. 



THE OSSEOUS SYSTEM, OR SKELETON. 



CHAPTER II. 

COMPOSITION AND STRUCTURE OF BONE, ETC. 

1. Composition of Bone. — Bone is composed of organic 
and inorganic matter, or in other words of animal and 
earthy matter. The animal matter is largely gelatine ; 
the earthy is principally phosphate of lime, with some 
carbonate of lime and small portions of other earthy 
material. 

2. The proportion of animal and earthy matter varies 
with the age of the person. In infancy the animal matter 
predominates, the bones being soft and constituted chiefly 
of cartilage in which earthy matter is afterward deposited. 
Later in childhood the animal and the earthy matter are 
about equal, each forming one-half the weight of the bone. 
In adult life, or in middle age, about four-fifths of the 
bone is earthy ; in extreme old age the bones are still 
more largely composed of mineral matter. 

3. The bones of the very young, composed largely of 
gelatine, will frequently bend instead of break when sub- 
jected to violence, and hence are liable to be distorted by 
confinement in improper positions or by pressure upon 
them. In adult life the bones are strongest and firmest, 
though retaining a degree of elasticity. In old age the 



12 ACADEMIC PHYSIOLOGY. 

bones become very brittle and liable to fracture, and when 
broken heal slowly and often with difficulty. Thus are 
shown the uses of the composing materials — the earthy 
material giving firmness, and the animal matter tenacity 
and elasticity to the perfectly developed bone. 

4. In healthy bone the proportions of organic and inor- 
ganic matter are such as to give elasticity combined with 
sufficient firmness. In the disease called Rachitis or 
"Rickets," there is a deficiency of the earthy matter, and 
the bones being therefore too pliable and soft, deformi- 
ties ensue, such as bow-legs, badly formed arms, ribs, etc. 

5. Structure of Bone. — Excepting the joint surfaces, which 
are covered with cartilage, the bones are covered with a 
thin, tough, white membrane, known -as the periosteum 
(Gr. peri, around ; and osteon, bone), or bone-covering. 
This membrane adheres very closely to the bone, and in 
it ramify the blood vessels which supply nutrition to the 
bone. 1 From these blood vessels smaller branches pene- 
trate into the substance of the bone through small 
apertures called Haversian canals (from Havers, the 
anatomist, who discovered them). 

6. As the periosteum is the source from which the bone 
receives its supply of nourishment or building material, a 
portion of bone or even an entire bone may be removed, 
and, if the periosteum is saved intact and in place, new 
bone will be developed and replace the bone removed. 
As an example, we cite the case of a woman whose lower 
jaw-bone having become diseased, it was found necessary 
to remove it. The operation, performed by the late Dr. 
James R. Wood, of New York, was successful ; the peri- 

1 When a bone is severely bruised, inflammation sometimes takes place in the 
bone-covering and a painful felon results. 



THE OSSEOUS SYSTEM. 1 3 

osteum being saved and kept in place, a new jaw-bone 
was produced in due course of time. 

7. The long bones are composed externally of a dense 
layer of bone tissue, ivory-like in texture, enclosing a 
hollow space or canal. Their extremities are widened to 
form the joint surfaces, and are covered with cartilage. 
The hollow shaft is filled with a pinkish, fat-like substance 
called marrow. Blood vessels ramify through it and 
furnish nourishment to the inner surface of the shaft. 
Designed to serve as columns or as levers, the long bones 
are admirably adapted to this purpose. Their hollow 
form gives lightness, and, at the same time, greater 
strength than the same amount of bone would have in a 
solid form of equal length. 

8. The short bones are composed of a hard, ivory-like 
layer externally, and are softer or spongy in texture 
within. They are comparatively light in weight, and are 
found in parts where only a limited motion is required. 

9. The flat bones comprising those of the skull and 
other cavities, are composed of two layers of hard bone 
tissue which enclose spongy bone substance. They are 
adapted to surround and protect various internal organs 
of the body. 

10. Cartilage. — The cartilages belong to the bony system, 
and are what might be called fibrous tissue in a state of 
change to bone substance ; but all cartilage is not destined 
to be changed into bone tissue. Cartilage is tough, 
elastic, flexible, and either yellowish-white or pearl-white 
in color. It forms the surfaces of bones in movable 
joints, furnishing a smooth, glistening surface, and unites 
bones at points where the frame-work must yield to ex- 
pansion, as in the chest. It also forms the flexible skele- 



14 ACADEMIC PHYSIOLOGY. 

tons of certain parts, as those of the external ear, nose, 
eyelids, etc. 

11. Growth and Repair of Bone. — There is a vast difference 
between living bone and dead bone. We usually obtain 
our ideas of the bones comprising the human frame from 
the dried, bloodless specimens we see in museums and lec- 
ture rooms. Living bone, being well supplied with blood 
by the blood vessels of the periosteum and the marrow, is 
of a pale pink color on the surface, and deep red within. 

12. At the ends of the smaller canals of the bone lie the 
little cells, and these absorb nourishing and repairing 
material from the blood. The bones are built up, and 
eliminated particles are replaced by others, in the same 
way that the nourishment and repair of the softer tis- 
sues are accomplished. The cells of the bones have the 
special function of selecting from the blood that which is 
necessary to form bone tissue. 

13. The constant change of particles in the tissues can 
be easily demonstrated by the change of color that may 
be produced in bone by mixing madder with the food of 
animals. The bones soon become red. This color disap- 
pears when the coloring matter is withheld for a time, but 
reappears when the food is again colored. 

14. Repair of Broken Bone. — A broken bone is healed by 
the active work of the cells that remain uninjured. 

When the ends or edges of the fragments are properly 
placed together or "set," healing proceeds by a natural 
process, the bone being repaired in the same manner in 
which it grows. The cells send out first a watery fluid 
between and about the fractured ends. In the course of 
a few days this fluid becomes thicker, more jelly-like, and 
is gradually hardened by mineral matter which the cells 



THE OSSEOUS SYSTEM. 15 

deposit. In a few weeks the deposited matter becomes 
firm enough to hold the bones in place. The new mate- 
rial deposited does not, however, become as hard and firm 
as the old bone for several months, and hence it is requi- 
site to exercise care in the use of the injured bone during 
that period. 

15. The process of healing varies in length of time 
with the age and general condition of the individual, being 
more rapid in the young than in the old. In advanced 
age fractures are sometimes exceedingly slow in reuniting, 
and in some cases union cannot be effected at all : in this 
way is indicated the general decline of the vital reparative 
processes in the aged. 



CHAPTER III. 

THE SKELETON. 

1. The Skeleton and its Functions. — The word skeleton (from 
Gr. skello, to dry) signifies literally the dry or hard parts 
of the body. When used ordinarily, it applies merely 
to the bones ; but in a broader sense it includes not only 
the bones, but the cartilages and membranes which com- 
plete the framework of the body. By some anatomists 
the teeth are also considered as belonging to the skeleton. 

2. The skeleton serves as a basis of support for the soft 
parts, affords surfaces of attachment for muscles, protec- 
tion for many delicate organs, and gives general outline 
to the body. The bones composing it vary in size and 
shape according to their location and office, and are bound 
together by fibrous bands, called ligaments. In the adult 
there are about two hundred separate bones, not including 



i6 



ACADEMIC PHYSIOLOGY. 



the teeth and the small bones of each ear. In the child 
they are more numerous ; and in the process of develop- 
ment of the skeleton, certain bones become united. 

3. For convenience in classification the bones are di- 
vided into those of the heady trunk, the upper and the low- 
er extremities. The head has twenty-two bones, the trunk 
fifty-two, the upper extremities sixty-four, and the lower 
extremities sixty-two. i 




Fig. 2. — The Skull {Front View). 
2, parietal bones; 3, temporal bones; 4, portions of the sphenoid bones, 
5, nasal bones; 6, superior maxillary bones; 



1, frontal bone 
forming the backs of the orbits of the eyes 
7, inferior maxillary bone ; 8, malar or cheek bone 



THE OSSEOUS SYSTEM. 1 7 

4. The Head. — The bones of the head are subdivided 
into those of the cranium or skull, and those of the face ; 
of the former there are eight, and of the latter fourteen. 

5. The bones of the skull axe separate in infancy and child- 
hood ; but in the adult they become firmly united by irreg- 
ular, immovable joints called sutures (Lat. sutura, from 
suere, to sew or stitch), and thus form a strong, rounded 
case for the lodgement and protection of the brain and the 
organs of the special senses. These bones have been 
named according to their shape or location, as follows : 
the occipital bone, at the back and base of the skull, con- 
tains an aperture for the passage of the upper part of the 
spinal cord, and sends off two projections which join with 
the first bone of the spine to provide for the nodding 
movement of the head ; the two parietal bones form the 
sides and top of the skull ; the frontal bone forms the 
front of the skull and parts of the cavities of the nose 
and the orbits of the eyes ; the two temporal bones form 
part of the sides and base of the skull, and contain the 
cavities of the organ of hearing ; the sphenoid bone, re- 
sembling a bat with outstretched wings, forms the central 
portion of the base of the skull ; the ethnoid bone, located 
in the front part of the base of the skull, forms part of the 
cavities of the nose and the inner boundaries of the orbits 
of the eyes. In addition to these are the four small bones 
of the middle cavity of the ear. 

6. The inner surface of these bones is marked with 
numerous elevations and depressions which correspond 
with similar inequalities on the surface of the brain. 

7. The bones of the face comprise two bones of the bridge 
of the nose, two lachrymal bones at the inner angles of 
the orbits of the eyes, two cheek-bones, two bones of the 



i8 



ACADEMIC PHYSIOLOGY. 



upper jaw, one of the lower jaw, two of the palate, two 
turbinated or scroll-like bones in the cavity of the nose, 
and the vomer, or plough-share, the thin sheet of bone 




EXPLANATIONS. 

a, a, the coronal suture. 

b, the sagittal suture. 

c, the lambdoidal suture. 

d, d, ossa triouetra, small ragged bones, 
occasionally found in some skulls, lying in the 
last-mentioned suture. 

e, e, portions of the temporal bone, over- 
lapping the walls. 

i , the frontal bone, 

2, 2, the parietal bone. 

3, the occipital bone. 



Fig. 3. 

which separates the cavities of the nose. These bones 
unite with the bones of the skull, and form the cavities in 
which the organs of sight, hearing, taste, and smell are 
placed. 

8. The Teeth. — Although the teeth are not commonly 
classed as bones, they apparently belong to the osseous 
system. They differ greatly in size and form. Those in 
the front of each jaw have sharp chisel-like edges, are 
thus well adapted to biting or cutting, and are called in- 
cisors (Lat. incido, I cut). Next to these in each jaw and 
on each side is a single pointed tooth, called the canine 
(Lat. ca?iis y dog) because its form and position in the 
human jaw correspond with the similar tearing teeth of 
the dog and other flesh-eating animals. Beyond the canine 
teeth on each side is a pair of bicuspids (Lat. bis, twice ; 



THE OSSEOUS SYSTEM. 19 

and cuspis, a point), so called because of two ridges on the 
crown of each tooth. Still beyond are larger teeth, each 
having a broad, irregular, grinding surface, and these are 
called molars (Lat. mola, a mill). 

9. At birth the teeth are undeveloped, but during the 
first two or three years of childhood twenty deciduous or 
temporary teeth are developed. Of these eight are inci- 
sors, four canine, and eight molars. At the age of about 
seven years the temporary teeth begin to be cast off, 
their places being taken by the permanent teeth which 
grow beneath them ; and by the twelfth or thirteenth year 
all have in this way given place to the second, or perma- 
nent set. 

10. The permanent teeth of the adult number thirty-two. 
In each jaw there are four incisors, two canines, four bi- 
cuspids, and six molars. The last molars, however, do not 
appear till between the eighteenth and twenty-first years, 
and occasionally one or other of them may not appear till 
several years later. This fact has caused these latter to 
be called " wisdom teeth." 

11. A tooth is composed of four distinct substances, 
viz., the pulp, the dentine or ivory, the enamel, and the 
cement. The cavity of the tooth contains a very soft 
substance, the pulp, which consists of a mass of minute 
blood-vessels and nerves that enter. through an opening at 
the point of each fang. The dentine or ivory (Lat. dens, 
a tooth), which envelops the pulp, resembles bone, but 
contains much more mineral matter, and is consequently 
harder. 

12. The dentine, which forms the crown of the tooth, is 
overlaid with the enamel, the hardest substance in the 
body, containing only two or three per cent of animal 



20 ACADEMIC PHYSIOLOGY. 

matter. The root of each tooth is surrounded by the cem- 
ent > a substance softer than dentine, and which resembles 
bone in structure, though it has no Haversian canals. 

13. It has already been intimated that the different 
classes of teeth are adapted for different modes of action. 
The variety of action is increased by the movement of the 
lower jaw. In biting our food, the jaw moves perpendicu- 
larly and brings into use the front or incisor teeth. After 
being severed by the incisors, the food is passed to the 
molars to be crushed and ground, and this grinding could 
not be thoroughly accomplished if the lower jaw were capa- 
ble of a vertical motion only. While grinding the food 
it may be observed that the jaw moves a little to the right 
and left, and also backward and forward, these movements 
causing the surface of the molars to slide over each other, 
and thus to grind the food that may be between them. 1 



CHAPTER IV. 

the skeleton (continued). 

1. The Trunk. — The bones of the trunk comprise the 
spinal column or backbone, the rids, the sternum (Gr. ster- 
non, the breast) or breast-bone, and the hyoid bone at the 
root of the tongue. There are twenty-six bones in the 
spinal column, twenty-four ribs, one sternum, and one 
hyoid bone. 

1 The carnivorous animals have not broad molars ; they bite and tear the flesh on 
which they feed, the general motion of the jaw being up and down only. On the 
other hand, herbivorous animals have large, broad molars, and the jaw has a much 
greater variety of movement than that of the human being. 



THE OSSEOUS SYSTEM. 



21 



2. The spinal column consists of a 
series of irregular bones, twenty-four 
of which are called vertebra (Lat. 
verto, I turn). The lowest two are 
called the sacrum (Lat., sacred) and 
the coccyx (Lat., cuckoo). There are 
originally thirty-three separate ver- 
tebrae in the column, and the upper 
twenty-four commonly remain dis- 
tinct throughout life ; but the bones 
from the twenty-fifth to the twenty- 
ninth, inclusive, early unite into one 
large bone, the sacrum ; and the four 
remaining vertebrae often fuse into one 
mass, the coccyx. 

3. The vertebrae are so united as 
to form a long, flexible column, which 
serves as a centre or axis with which 
all the other bones of the frame-work 
are connected. The base of the skull 
rests on the uppermost bone of the 
column, the lower extremity of which 
is wedged in between the bones of the 
hips. 

4. The uppermost seven bones are 
called cervical vertebrae (Lat. cervix, 
the neck). The next twelve are 
named dorsal vertebrae (Lat. dorsum, 

EXPLANATION. 

Longitudinal section of the Spinal Column, viewed 
from the right side. — C to D, cervical vertebra ; D to L, 
dorsal vertebra ; L to S, lumbar vertebra ; S to Co, sacral 
vertebra ; Co to 4, coccygeal vertebra. In life, the spaces 
between the bones are occupied by cushions of cartilage. 



Fig. 4. 



22 ACADEMIC PHYSIOLOGY. 

the back). The remaining five movable bones are 
termed lumbar vertebrae (Lat. lumbus, the loin), these 
latter being the largest of the series. Their bodies are 
broad and thick and closely interlocked by broad plates 
extending down from behind and at their sides. 

5. The sacrum, so called from its having been anciently 
offered in sacrifice and hence considered sacred, is the 
wedge-like bone next below the lumbar vertebrae and 
between the hip-bones. 

6. The coccyx, so named from its resemblance to the 
beak of a cuckoo, is the slender appendage of bone forming 
the lower and of the spinal column. An extension of the 
coccyx constitutes the flexible tail in some of the lower 
animals. 

7. A vertebra consists of a body from which spring two 

EXPLANATION. 

This is an accurate drawing of one of the bones of 
the spine, at the neck. 

a is the body of the bone. 

o, the spinous process, or handle, which gives the 
name of spine to the whole column. 

c, c, the transverse processes, to which the muscles 
adhere, producing motion. 

d, d, round holes, through the arms of the bone, 
for safely lodging an artery, which carries blood to 
the brain. 

e, e, the upper, and /, /, the under, surfaces, which 
make a joint with the blocks above and below it. 

g, the hole through which the spinal marrow, or pith of the back, passes in safety from the 
head, through the whole chain of twenty-four vertebrae. 

arches, that unite in such manner as to form a ring. From 
the outer edge of this ring three processes or spines are 
given off, one at the back and one at each side. These 
spines afford places of attachment for ligaments and for 
muscles that bend the back, etc. Though the vertebrae of 
the various regions of the column differ in certain details, 




THE OSSEOUS SYSTEM. 23 

they resemble each other so greatly that, for our purpose, 
a general description of one will serve for all. 

8. The vertebral bones are united by disks of elastic 
cartilage interposed between them, thus rendering the col- 
umn flexible and lessening shock from blows and jars. In 
advanced age, these cartilages become harder and less elas- 
tic, and hence the back bends with less ease. 

9. It will be evident that the vertebrae arranged in a 
column and bound together by strong ligaments will not 
only afford powerful and flexible support, but that the 
space in the centre of the bones, in the continuity of the 
column, forms a long tube. This tube, called the spinal 
canal, lodges the great trunk-nerve known as the spinal 
cord, and affords it strong and much-needed protection. 

10. A. side view of the spinal column shows it to be 
curved somewhat like the letter /, but when viewed from 
back or front there is no lateral curvature. The curves of 
the column add to the safety of the brain in the jolts and 
jars to which the body is liable, the shock of a fall or of a 
leap being divided in force at each curve, instead of being 
transmitted directly, as would be the case if the column 
were straight ; and further, the curve at the back serves 
to increase the cavity of the chest, giving space for the 
expansion of the lungs; at the loins the forward curve 
operates to give better support to the contents of the abdo- 
men. 

11. In each of the vertebrae there are notches which, 
when the bones are in place, form little canals that give 
passage to nerves that spring from the spinal cord and are 
distributed to the various parts of the body : other simi- 
lar channels provide safe passage for blood vessels. 

12. How the Head turns. — The head is enabled to turn 



24 



ACADEMIC PHVSIOLOGV. 



right or left on the spinal column by means of mechanism 
briefly described as follows : The second vertebra of the 
neck, the axis, has a peg-like projection (the odontoid pro- 
cess) which extends upwards and forms an axis on which 
the uppermost vertebra, the atlas, turns, its front, inner 
surface being kept in position against the peg by a strong 
ligament. In turning, the head and the atlas-bone move 
together without danger of falling either forward or back- 
ward, an accident which would immediately destroy life by 
crushing the spinal cord. 

13. The Thorax or Chest. — The ribs, twenty-four in num- 
ber, twelve on each side, are divided into two general classes, 

the true and the false. 
They are all attached by 
movable, flexible joints 
to the vertebrae behind, 
and the uppermost seven 
on each side, the true ribs, 
are separately united by 
bands of cartilage to the 
breast-bone in front. The 
remaining five on each side 
are called the false ribs, and 
of these the uppermost 
three are joined together 
in front by a common car- 
tilage and by it to the 
breast-bone. The last two 
on each side are free in 
front, and hence are 
known as floating-ribs. In general the ribs are flat and 
curved, and gradually increase in length from the first to 




Framework of the Chest as it appears 
when not distorted by tight lacing. — i, the 
sternum or breast-bone ; 2, 2, the ribs ; 3, the 
spinal column. 



THE OSSEOUS SYSTEM. 



25 



the seventh. They incline forwards and downwards 
from the backbone, so that when alternately raised and 
depressed in breathing the capacity of the chest is corre- 
spondingly increased or diminished. 

14. The ribs, the breast-bone, and the upper portions of 
the backbone together form the elastic, bony frame-work 
of a cage, the thorax or chest, which surrounds and pro- 
tects the heart, lungs, and large blood-vessels. The inter- 
stices of this cage-like structure are filled with muscles 
which cover and form with it the walls of the chest. 

EXPLANATION. 

This figure represents the sternum, or breast-bone. 

A, the place where the collar-bone is joined. 

C, where the first rib is joined. 

c, d, e, f, g, the number of pieces which are united into one. 

k, the tip of the sternum. 

15. The sternum (Gr. sternon, the 
breast), or breast-bone, is flat in shape 
and spongy in texture. It affords at- 
tachment for the cartilages of the 
ribs, and completes the formation of the 
chest in front. Originally it consists of 
several bones, which ultimately become 
united in one. 

16. The size of the arches formed by 
the pairs of ribs increases from above 
downwards, the shape of the chest being 
that of a cone, the base being down- 
wards. At least this is its shape when 
not deformed. 

17. The hyoid bone at the root of the tongue received 
its name from a fancied resemblance to the Greek letter 
Upsilon, whose shape is somewhat similar to that of a 




26 ACADEMIC PHYSIOLOGY. 

horse-shoe. It provides attachment for a number of mus- 
cles of the neck and tongue. 

18. The Upper Extremities. — The upper extremities are 
the long, jointed appendages attached to the upper part of 
the trunk, and commonly called the arms. Together they 
contain sixty-four bones, thirty-two on each side, and 
these are classified as bones of the shoulder, arm, fore- 
arm, wrist, and hand. 

~J*.^ \ e , EXPLANATION. 

/J|||||m^v jfc^^* i ijli% I n tn ' s cut i s seen tne un ion of the head of the humerus 

WW MitlinW9mK^ P-'V^2fit^l wu h tne shallow socket of the scapula. These bones are 

J ■'///// '*^i!lliF ■ 1 represented as detached from the body, and the view is a 

I j' h "i//'' ^ Ilrar if J a > tne huments, or arm-bone. 

V WW 1 1 I ^' the sca /' ula > or shoulder-blade. 

\ 'Mmi/Wl Cf the head or ^ a11 oi tne humerus. 

V ^ul/rjJr j d, rim of the socket of the scapula. 

b a e , processes of bone that overlap and protect the joint. 

Fig. 8. 

19. Each shoulder contains two bones, the clavicle 
(Lat. clavis, a key), so named from its resemblance to an 
ancient key, and commonly known as the collar-bone ; 
and the scapula (Lat., the shoulder) or shoulder-blade, 
the broad, flat, triangular bone at the top and back of 
the chest. One end of each clavicle joins the top of the 
breast-bone, and the opposite end joins the shoulder-blade, 
thus acting as a brace to prevent the shoulder from inclin- 
ing unduly toward the chest. The scapula has no joint 
with the chest, but is held in position by strong muscles 
which cross and overlap it in various directions ; it is mov- 
able in a variety of directions. A shallow cavity in each 
scapula receives the rounded head of the bone of the arm, 
and with it forms the shoulder-joint. Bony projections over- 



THE OSSEOUS SYSTEM. 



27 



lap the joint, give it additional security, and afford attach- 
ment for ligaments. The shallowness of the cavity of the 
shoulder-joint gives it the greatest range of movement, 
but also renders it more liable to dislocation. 

20. The arm (upper-arm) contains one long bone, the 
humerus (Lat., the arm), enlarged at its extremities to pro- 
vide joint surfaces at the shoulder and the elbow. The 
shaft of this bone is surrounded by powerful muscles 
which use it as a lever. 

EXPLANATION. 

All the bones of the arm, fore-arm, 
and hand, are here exhibited in con- 
nection, with reference to impressing 
it on the mind, after having read a 
short description of the individual parts 
of the upper extremity. 

a is the head of the arm-bone, artic- 
ulated to the shoulder. 

b, the joint, or elbow, formed by the 
ulna and lower end of the arm. 

c, the shaft of the os humeri, or arm. 

d, the radius, or handle of the hand, 
united solely to the wrist. 

e, the ulna, which alone forms with 
the arm the joint. 

21. The fore-arm has 
two bones, the ulna 
(Lat., the elbow) and 
the radius (Lat., a ray 
or a spoke), which ex- F,g ' 9 ' 

tend from the elbow to the wrist. In addition to enter- 
ing into the formation of the elbow-joint, they join 
the carpal bones to form the wrist-joint, and with each 
other at both extremities in such a way as to admit of 
the rotary motion of the hand. The ulna (the bone on 
the little-finger side of the arm) enters principally with the 




28 



ACADEMIC PHYSIOLOGY. 




humerus in forming the elbow-joint, as the radius does 
not touch the humerus till the fore-arm is drawn up to the 
arm. The radius, however, is so expanded as to enter 
principally into the formation of the wrist-joint. In the 
rotary motion of the hand, the radius twists or glides over 
the ulna when the palm is turned upward or downward, 
and when the thumb is uppermost the bones are parallel. 

b a ex PLAN ATI ON. 

Another plan of the bones of the wrist, show- 
ing them placed in two rows. This is a back 
view of the carpus of the right hand. 

a, the boat-shaped bone ; 

by the half-moon shaped ; 

c, the -wedge-shaped ; 

d, the pea-shaped ; which make the upper row, 
joining the fore-arm. 

In the second row are the four others, e,f, g,h, 
which are united by a joint to the palm of the 
hand. 

22. The wrist has eight small, irregular, solid bones, 
bound together in such a manner as to give freedom of 
motion and great strength. They are called carpal bones 
(Gr. karpos, the wrist), and are arranged in two rows of 
four each. The rotary motion of the radius and the 
flexibility of the wrist give the hand great variety of 
movement. 

23. The liand contains nineteen bones, five being in the 
palm and fourteen in the fingers and thumb. The bones 
of the palm are called metacarpal bo?ies (Gr. meta, beyond ; 
and karpos, wrist), and those of the fingers and thumb, 
phalanges (Gr. phalanx, a rank), three of which form each 
finger, and two each thumb. The number, varying length, 
and numerous joints of the fingers and thumb render the 
hand a wonderful instrument for grasping large objects 
and for picking up small ones. Some writers have ex- 



THE OSSEOUS SYSTEM. 



2 9 



pressed the opinion that man is indebted mainly to his 
hand for his superiority over the rest of the animal crea- 
tion. Its perfection, however, 
would be useless in the absence 
of intelligence adequate to the 
direction of its operations. 

24. The superiority of the 
right hand, in most instances, 
is well known. It has been 
argued that its properties are 
due to the more direct and 
forcible supply of arterial blood 
to the right arm ; also that its 
superiority is the result of the 
more frequent exercise of the 
right hand. The distinction 
pertains, however, to the whole 
right side of the body. The 
left side is not only weaker 

. . . Here is presented a back view of all 

in mUSCle, but also in Vital Or the bones of the hand as they are con- 

constitutional properties. The nected with the eight little bones of the 

\ ■ r m wrist. 

organs of motion of the right 

side are usually better developed than those of the left, 
and disease attacks the latter more frequently. An 
equalized motion of the body is seldom seen in walking ; 
the tread of the left foot is usually less firm, a greater 
push is made by it, and the toe is not so much " turned 
out " as in the right. Exercise and training of the left 
extremities are especially necessary to compensate for any- 
thing lacking in natural endowment. 




Fig. 11. 
EXPLANATION. 



30 ACADEMIC PHYSIOLOGY. 



CHAPTER V. 

THE SKELETON (concluded^). HYGIENE OF THE BONES. 

1. The Lower Extremities. — The lower extremities are, 
like the upper extremities, long and jointed ; they are 
commonly known as the legs, and are united to the lower 
end of the spinal column by means of the bones of the 
hips. 

2. Each lower extremity is divided into a hip, thigh, leg, 
ankle, and foot ; together the lower extremities contain 
sixty-two bones, one bone entering into the formation of 
each hip, one in the thigh, three in the leg, seven in the 
ankle, and nineteen in the foot. 

3. The hip-bones are also called the innominate bones 
(Lat. in, not ; and nomen, a name) ; each contains a deep, 
cup-like cavity on the external surface, into which the 
rounded head of the thigh bone fits to form the hip-joint. 
The broad, bony basin formed by the hip-bones and the 
sacrum is called the pelvis, which supports the inter- 
nal organs of the lower part of the trunk, and is in turn 
supported like a bridge, the legs being the pillars. 

4. The femnr (Lat. femur, the thigh) or thigh-bone 
resembles the humerus of the arm in general form, but is 
much larger and stronger. At its upper extremity is a 
sphere-like head supported by a neck forming an obtuse 
angle with the body of the bone. The head of the femur 
is not entirely enclosed by the cavity of the hip-bone. 
An elastic rim of cartilage increases the size of the cavity, 



THE OSSEOUS SYSTEM. 



31 



and embraces the head of the femur so closely as to hold it 
in place by atmospheric pressure. But this cartilage alone 
would be insufficient to prevent displacement, and hence 
two ligaments hold the ball of the femur firmly in its 
socket. One of these, in the form of a short cord, lies 
within the joint and connects the ball with the centre of 
the socket ; the other is outside the joint, and surrounds 
it like a cap or bag. 

EXPLANATION. 
We have here an excellent representation of the up- 
per end of the femur, or thigh-bone, and half of the 
pelvis. The ball, or head, of the femur, supported by 
a neck which forms an obtuse angle with the body of 
the bone, is fixed in the socket of the os innominatum, 
filling the cavity, but not all enclosed by it. The depth 
of the socket is only about half the diameter of the 
ball. 

a, the os innominatum, or hip-bone. 

b, the head of the femur, or thigh-bone. 

c, the rim of the socket. 

d, the femur. 

e, the sacrum. 
f, the point of bone on which we sit. 

Fig. 12. 

5. The hip-joint, like that of the shoulder, permits 
movement in almost every direction, though not so freely 
as the latter, while the depth of its socket provides 
greater security against dislocation. Violent twistings 
of the limb, however, frequently force the ball from the 
socket. 

6. The leg has three bones, the tibia (Lat., a pipe or 
flute), the fibula (Lat., a clasp), and the patella (Lat., a 
little plate). The tibia, or shin-bone, is the largest, and 
gives the main support for the weight above it, as it alone 
enters with the femur into the formation of the knee-joint, 
and with the tarsal bones principally forms the ankle- 
joint. The fibula is the long, slender bone, firmly bound 





32 ACADEMIC PHYSIOLOGY. 

at both ends to the outer side of the shin-bone, its lower 
end forming the external side of the ankle-joint. 

7. The knee-joint is formed by the two rounded ridges 
of the lower extremity of the thigh bone being received 
into corresponding grooves in the upper 
end of the shin bone. Cartilages on the 
joint surfaces provide smoothness and 
diminish the jars to which the joint is 
liable, and strong ligaments within and 
without bind the bones very firmly toge- 
ther. In front of the joint is the patella 
or knee-cap, a chestnut-shaped bone held 
in place by the broad tendon of a muscle, 
and not directly joined to the bones be- 
neath it. This bone acts as a shield to 

THE KNEE-JOINT. ..... 

Fe the femur or' ^ c k nee -J 01n t, whose prominence and pe- 
thigh-bone; n, the culiar liability to injury from falls, and 

tibia, or shin-bone; . • ., • ,1 • it 

Ft, the fibula, or in various other ways, require this addi- 
siender bone of the ontial means of protection. 

or knee-pan; «, >' ^. The an ^^ e > situated at the lower ex- 
ligamems that sus- tremities of the bones of the leg, con- 
tain the patella. . . . . . 

tains seven short, irregular bones, called 
tarsal bones (Gr. tarsus, the ankle). The extremities of 
the leg bones united form a mortise, and into it receive 
one of the bones of the ankle, thus forming the ankle- 
joint. Strong ligaments here again bind the bones 
together. The movements of this joint are not so free 
as those of the wrist. The joint is peculiarly liable to 
sprains from rough twistings intensified by the weight 
of the body. 

9. The foot contains nineteen bones, viz., the five meta- 
tarsal bones (Gr. meta, beyond ; and tarsus, ankle) or 



THE OSSEOUS SYSTEM. 



33 



bones of the instep, and the fourteen phalanges in the 
toes. The bones of the instep of the foot are similar to 
those of the palm of the hand, and are connected with the 
bones of the toes. The number of bones in the toes is 
the same as in the fingers and thumb, the great toe repre- 
senting the thumb. All these bones are fastened together 
by ligaments. 

"If the foot and the hand are varieties of the same type 
of organization, they present differences in regard to their 
respective uses ; the foot, designed to support the body, is 




These three plans show how the two bones of the leg are united above the ankle-joint. 
*» 2 > 3> 4> 5> 7> 7> 6, mark the ligaments which bind them firmly. 

especially remarkable for its solidity ; in the hand, mobil- 
ity is the predominating quality." The toes have neither 
the length of the fingers nor the extent and variety of 
their movements ; in a word, it is a foot, and not a hand 
as it is in the quadrumana. Its arched form gives great 
strength combined with elasticity. 

10. Joints and Ligaments. — A joint is the union of two or 



34 ACADEMIC PHYSIOLOGY. 

more bones with each other, and may be either movable 
or immovable. The latter class are few in number, and 
will be noticed later. The movable joints receive differ- 
ent names according to their characteristics, viz., ball-and- 
socket joint, hinge joint, pivot joint, mixed joint, and 
sliding joint. 




By this diagram the skeleton of the foot will be clearly understood, even without the aid of 
the bones. Twenty-six bones are here so curiously grouped together, that an arch is made 
between the heel and ball of the great toe. 

a shows the five bones of the metatarsus. 

d, e, g, and h point out the bones of the instep, or tarsus. 

b and c indicate the phalanges, or toes. 

11. The ball-and-socket joints are those capable of mov- 
ing in all directions. Of the ball-and-socket joint there 
are two examples in the shoulders and two in the 
hips. 

12. The hinge joints are those in which the motion is 
limited to two directions, like that of the hinge of a door. 
The knee, elbow, and ankle present the largest examples 
of the hinge joint, and the joints of the toes, fingers, and 
jaw belong to the same class. 

13. The pivot joints are those which admit of a rotary 
motion, as that of the axis bone of the spine which per- 



THE OSSEOUS SYSTEM. 35 

mits of the rotary motion of the head, and that of the 
ulna and radius by which the latter bone rolls over the 
former. 

14. The mixed joints are such as admit of slight motion 
and great strength. The joints of the spinal column by 
which the forward, backward, and lateral motions of the 
trunk are made possible, and those of the ribs, vertebrae, 
and sternum which admit of motion during respiration, 
are examples of mixed joints. In these joints motion is 
made possible by means of the elasticity and flexibility of 
the cartilages which enter into their formation. 

15. The sliding joints are those in which the bones have 
a sliding or gliding movement, as seen in the ankle and 
the wrist. 

16. The immovable joints are those in which the mar- 
gins of the bones are almost in contact, and are incapable 
of motion on each other. Sometimes a thin membrane 
or a thin layer of cartilage is situated between the joint 
surfaces of the bones, but even these disappear in ad- 
vanced life, and a complete bony union is formed. Exam- 
ples of immovable joints are those of the skull, in which 
each bone has a very irregular, saw-like edge, and these 
edges interlock in joints called sutures (Lat. sutura, a seam). 
Most of the bones of the face are also united in immov- 
able joints. 

17. In all joints the bony surfaces which move upon 
one another are covered with cartilage, and between 
them there is a thin sac of membrane which covers or 
lines the cartilages and partially forms the side walls of 
the joints. This sac, called the synovial membrane (Gr. 
syn, together; oon, egg), secretes a small quantity of 
lubricating fluid, like the white of an egg, called the syno- 



36 ACADEMIC PHYSIOLOGY. 

vial fluid, the office of which is to lubricate or moisten 
the joint surfaces. 

18. The ligaments (Lat. ligo, I bind) are strong, white, 
fibrous bands which bind the bones together. Being more 
or less elastic, they allow the necessary freedom of mo- 
tion and tend to prevent dislocation. The muscles are 
united to the bones by other white bands called tcndo7is 
(Lat. tendo, I stretch), and these should not be confused 
with ligaments, which always bind bones together. Liga- 
ments are sometimes circular and surround the joint on 
all sides, as in the case of ball-and-socket joints. In 
some instances ligaments are situated within the joints, 
as in the hip-joint, where the round ligament unites the 
ball of the thigh-bone and the bottom of the socket in the 
hip-bone; or as in the knee, in which the ligaments 
cross each other obliquely between the bones of the joint. 
In hinge joints the ligaments are chiefly accumulated at 
the sides of the joints. 

19. The most perfect mechanism which man has been 
able to design and construct bears no comparison to the 
wonderful assemblage of apparatus comprised in the 
joints. 

20. The Envelope of the Skeleton. — The strange outlines of 
the skeleton, the type of death, are covered by and caused 
to disappear beneath an envelope of muscles and tegu- 
ments. The eyelids veil the orbit and protect the eye. 
The coverings of the nose complete its form, and protect 
the organs of smell. The lips, placed before the cavity 
of the mouth are at once an organ of prehension, an in- 
dispensable instrument in articulating sounds, and one of 
the most expressive features of the face. The external 
ear collects the sound waves, and gives expression to the 



THE OSSEOUS SYSTEM. 37 

head. The hair of the scalp, the eyelashes, and the eye- 
brows protect the skull and the eyes, and, by their varying 
shades of color, undulations, and curves, contribute to the 
sightliness of the whole. Lastly, the skin, enlivened by 
the most delicate tints, and strengthened by more vigor- 
ous tones, forms the outer envelope of the rest of the 
body. 

HYGIENE OF THE BONES. 

21. Primary Requisites. — To be healthy, bone, like the 
other tissues, demands that a proper balance in the vital 
processes of the system shall be maintained. Suitable 
food, its proper digestion and assimilation, unobstructed 
circulation of the blood, the proper absorption and ulti- 
mate elimination of waste products, and sufficient exer- 
cise, are primarily essential to healthy bone structure. 

22. Food that will supply in sufficient quantity and in 
due proportions the earthy and the animal constituents 
of bone is required. An undue preponderance of earthy 
matter gives to the bones brittleness, and renders them 
liable to be easily fractured ; while a superabundance of 
animal substance causes them to be too flexible and to 
yield too readily under pressure or weight imposed upon 
them, thus producing distortion and deformity. Diges- 
tion must be unimpaired in order that the constituents of 
bone may be thoroughly abstracted from the food ; the cir- 
culation of the blood must be normal in order that the 
elements held in solution shall be properly and sufficiently 
deposited ; and exercise must be taken to stimulate diges- 
tion and the circulation, and to strengthen the muscles, by 
the contraction of which the bones are kept in natural 
position and the frame-work preserved from deformity. 



38 ACADEMIC PHYSIOLOGY. 

23. Distortion through Faulty Position. — On account of the 
flexibility of bone and the readiness with which it yields 
in childhood, caution is always necessary to avoid con- 
tinued pressure upon any of the bones and the produc- 
tion of permanent alterations in their shapes. Habitual 
faulty positions in sitting and in standing likewise tend 
to distortion of various bones, to " round shoulders," 
" hollow chests," and to improper curvature of the spine. 

24. Lateral curvature of the spine is produced by abnor- 
mal muscular contraction in which the spinal processes 
on one side are drawn toward each other, and the carti- 
lages between the bones are compressed on the concave 
side of the bent spine. This deformity is almost invari- 
ably the result of continued improper position. Those 
who lean to one side habitually, as for instance, with one 
arm elevated on a high desk at school, are the most liable 
to it. Weakening of the muscles of one side of the back, 
sufficient to prevent their action for some time, may be 
followed by permanent contraction of those on the oppo- 
site side, and consequent deformity. Shortening of one 
leg from any cause will also give rise to lateral curvature 
of the spine. 

25. It is of the greatest importance that young people 
should always sit erect, allowing balanced muscular action, 
for careless habits of sitting are sure to result in some 
degree of spinal curvature and deformity, if not in disease. 
Properly regulated gymnastic exercises, calling into use 
the weakened muscles, may correct incipient curvature of 
the spine. 

26. Distortion by Dress. — Through false notions of what 
constitutes symmetry of form, many consider a small waist 
to be a special mark of beauty and grace, and in order to 



THE OSSEOUS SYSTEM. 



39 



secure it resort is had to a process of compression analo- 
gous to that by which the women of China are caused to 
have small, and, according to their idea, beautiful feet. In 



Contracted Chhst. 

An outline is here presented of the chest of a female, to 
show the condition of the bones, as they appear after death, 
in some women who have habitually worn tight stays. 

All the false ribs, from the lower end of the breast-bone, 
are unnaturally cramped inward towards the spine ; so that 
the liver, stomach, and other digestive organs in the imme- 
diate vicinity, are pressed into such small compass that their 
functions are interrupted, and, in fact, all the vessels, bones, 
and viscera on which the individual is constantly depending 
for health, are more or less distorted and enfeebled. 




Fig. 16. 



order to secure a small waist, girls are tightly laced before 
the bones of the chest are fully developed. This presses 
inward the lower ribs, so that which is naturally the 
largest part of the chest is made the smallest, and various 
internal organs are crowded out of place and so com- 
pressed as to interfere with their operations. 

Skeleton of a well-formed Female Chest. 

By comparing the accompanying plan of a well-devel- 
oped and naturally proportioned female chest, with the 
distorted skeleton appended to the preceding note, the 
difference is strikingly apparent. Here is breadth, space 
for the lungs to act in ; and the short ribs are thrown 
outward, instead of being curved and twisted down 
towards the spine, by which ample space is afforded for 
the free action of all those organs which in the other 
frame were too small to sustain life. The first may be 
regarded as the exact shape and figure of a short-lived 
female ; and this may be contemplated as an equally 
true model of the frame of another, who, so far as life 
depends upon a well-formed body, would live to a good 

Fig. 17. ° ldage - 

27. The size of the chest being diminished, and the 
muscles that move the ribs being hampered and weakened 
by enforced inactivity, proper respiration becomes impos- 




40 ACADEMIC PHYSIOLOGY. 

sible. Blood circulation is interfered with by pressure 
upon important blood-vessels, and the purification of the 
blood is retarded through insufficient breathing. When 
this process of lacing is persisted in, many of the natural 
functions of the body become seriously and permanently 
impaired. 

28. Diseases of the Bones. — It would hardly be suspected 
from the appearance of bone, that, throughout life, and 
more particularly in early life, it is the seat of an active 
vital process, and that it is liable to inflammation, ulcera- 
tion, and death, the same as the softer tissues of the 
body. 

29. Inflammation of the periosteum and bones is often 
produced by direct injuries from falls and blows, or by the 
inoculation of specific poisons. A felon of the hand is a 
result of such injury and inflammation. When the affected 
bone lies close to the skin, redness and swelling are pres- 
ent, pus may form, and the severe throbbing pain will 
continue for a long time. Rest and hot fomentations are 
necessary from the start, and surgical treatment should 
be employed. 

30. Ulceration of the bones, or eai'ies, is a result of in- 
flammation. As the ulceration progresses, destruction of 
the bone tissue results in the formation of matter which 
gradually works its way to the surface and is discharged 
through openings in the skin. If the diseased condition 
is allowed to continue, the bone becomes so affected that 
its usefulness is destroyed. An operation which consists 
in scraping the bone to remove diseased tissue is required, 
as no other treatment will arrest the progress of the 
disease. 

31. Death of a large portion of bone, or as it is technically 



THE OSSEOUS SYSTEM. 41 

termed, necrosis, is sometimes one of the terminations of 
inflammation. A large section of dead bone is separated 
from the rest of the bone, and thus becomes a foreign 
body which nature makes an effort to throw off, as in the 
case of ulceration. As it would require months or years 
to accomplish this removal by natural processes, surgical 
skill removes it in a few minutes by a simple operation, 
and with proper after-treatment, new bone is produced. 

32. Softening of the bones may take place after inflam- 
mation, or from deficiency of earthy material. This con- 
dition of the bones is most frequently encountered in 
children, the bones of the legs bending from the weight 
of the body and producing a deformity called " bow-legs." 
In the disease called rickets, the bones are similarly soft, 
but there is a deficiency of both animal and earthy matter 
in the bones. These deficiencies must be supplied by 
food that contains the lacking constituents in abundance. 
When deformity has developed, mechanical appliances 
should be attached to the leg and foot to aid in reducing 
the unnatural curvatures. 

33. Sprains, Dislocations, and Fractures. — A sprain is a torn 
or stretched condition of the ligaments of a joint, com- 
monly caused by falls, blows, or sudden wrenching. 
When severe, a sprain may prove more serious than 
either a dislocation or a fracture. The treatment of 
sprains requires absolute rest of the injured part. When 
the injury first occurs, cold applications will often prevent 
inflammation. After swelling has taken place hot fomen- 
tations should be applied, and the limb kept in an elevated 
position. Neglected sprains are liable to lead to serious 
chronic diseases of the injured joints. 

34. A dislocation is a separation of the extremities of 



42 ACADEMIC PHYSIOLOGY. 

bones that form a joint, and may result from external 
forces, or from muscular contraction. The indications of 
a dislocation are deformity of the joint, loss of function, 
and the absence of the grating sound heard in fractures. 
A dislocation should be reduced before much swelling 
takes place. 

35. Fracture of a bone may be produced by various 
external violence or by muscular contraction. Grating 
sounds and sharp pain at the point of injury when the 
part is moved, mobility where there should be no motion, 
and deformity of the part, point conclusively to the occur- 
rence of a fracture. The bones should be restored to 
their natural positions and fastened there with suitable 
bandages, promptly and before inflammation begins. If a 
surgeon cannot be had at once, the injured person should 
be placed on a board or shutter, the injured part disposed 
in the most comfortable position possible, and then con- 
veyed to his home. After the bones have been set and 
the splints and bandages applied, the dressings should not 
be disturbed in the absence of a surgeon. The process of 
healing varies in time required according to the age and 
general condition of the individual. Usually about two 
months is required, and the injured part should be excused 
from duty during this period, and employed with caution 
for some time thereafter. 

36. Care of the Teeth. — By the teeth the food is divided 
and ground and thus adapted for the action of the gastric 
juice of the stomach. " Bolting " of food is often the 
beginning and cause of serious digestive disorders. Hence 
attention to the health of the teeth, by keeping them clean 
and in good order, is a measure which undoubtedly tends 
toward the prevention of disease. 



SUGGESTED POINTS FOR QUESTIONS. 43 

37. Particles of food allowed to collect and remain 
lodged between the teeth, decay and generate acids which 
attack the substances of the teeth and decompose them. 
Such 'particles should be thoroughly removed by means 
of a thread or by a wooden tooth-pick, after eating, and 
the teeth should be well brushed both on their inner and 
outer surfaces, as frequently. A moderately hard and 
broad brush should be used ; and as fluids are not suffi- 
ciently effective in cleansing the teeth, a powder or den- 
tifrice must be used. The fine precipitated chalk, or 
magnesia, forms a safe, agreeable, and effective tooth- 
powder. When the gums are tender, a small quantity of 
tincture of myrrh may be added to water and used as a 
mouth wash. On the first indications of decay, the den- 
tist's services are necessary ; and when the natural teeth 
have become unfit to perform their highly necessary work, 
there should be no delay in procuring efficient artificial 
substitutes. 



Suggested Points for Questions. 

Chapter II. — i. Composition of bone, organic and inorganic. 2. Pro- 
portions of animal and earthy matter at different ages. 3. Bones in youth, 
distortion; bones in the adult, strong; bones of the aged, brittle. 4. Elas- 
ticity and firmness; "Rickets," etc. 5. Bone coverings; periosteum; 
Haversian canals and blood-vessels; nutrition of bone. 6. Reproduction 
of bone when removed. 7. Structure of long bones, extremities, shaft, 
marrow, lightness, strength. 8. Short bones, structure, location. 9. Flat 
bones, layers, adaptation. 10. Cartilages, texture, color, uses. II. Living 
bone and dead bone. 12. Cells of the bones, where; nourishment, how 
accomplished. 13. Change of particles, demonstrated — madder. 14. Unin- 
jured cells and healing; time and care required. 15. Influence of age on 
healing; general decline indicated. 



44 ACADEMIC PHYSIOLOGY. 

Chap. III. — I. The term skeleton; application of. 2. Functions; size 
and shape of bones; ligaments; number of bones; union of separate bones. 
3. Divisions of skeleton, number of bones in each. 4. The head, divisions 
of. 5. The skull in infancy; sutures; bones of skull — location. 6. Inner 
surfaces. 7. Bones of face; relation to skull. 8. The teeth, classes, pecu- 
liarities, uses. 9. Temporary teeth, when, nUmber of. 10. Permanent teeth, 
classes and number; "wisdom teeth." 11. Structure of teeth — pulp, den- 
tine, enamel, cement, cavity, blood-vessels and nerves. 12. Arrangement 
of substances. 13. Variety of action of teeth; movements of jaw and 
effects. 

Chap. IV. — 1. Bones of trunk, classes and number. 2. Spinal column, 
original number of bones, fusing of bones. 3. Vertebra;, number, how 
united, form what, uppermost bone, lower extremity where. 4. Regions 
of the spinal column; interlocking. 5. Sacrum, what, where. 6. Coccyx, 
what, where; extension of. 7. Structure of a vertebra — arches, spines, 
attachments, ligaments, muscles. 8. Vertebral cartilages — blows and jars; 
hardening in age. 9. Spinal canal. 10. Curves of backbone; force of 
shock divided; increase cavity, afford support. II. Nerve and blood-vessel 
channels. 12. Turning of the head; axis, atlas, odontoid peg. 13. Ribs, 
number, joints, true ribs, false ribs, floating ribs; length and direction; 
capacity of chest increased and diminished. 14. Chest, how formed; pro- 
tection; muscles of walls. 15. Sternum, form, structure, attachments, bones 
in originally. 16. Arches of chest, form of. 17. Hyoid bone, form, 
attachments. 18. Upper extremities defined; number of bones of; divis- 
ions of. 19. Shoulder bones, clavicle, scapula; structure of shoulder-joint; 
dislocation of. 20. The arm, humerus. 21. Forearm; ulna and radius at 
elbow and wrist; rotary motion of hand. 22. Structure of wrist; variety of 
movement of hand. 23. Bones of hand, number, classes; the hand as an 
instrument. 24. Superiority of right hand; right and left side compared; 
unequal motion; exercise, etc., of left extremities. 

Chap. V. — 1. Lower extremities defined; joined to what. 2. Divisions 
of lower extremity; number of bones in. 3. Hip-bone, structure, socket; 
pelvis. 4. Femur, structure of — ball, cartilages; atmospheric pressure on 
joint; ligaments of hip-joint and offices. 5. Motion of hip-joint, depth of 
socket; twistings and dislocation. 6. Bones of leg — tibia, fibula, patella — 
entering into formation of knee, ankle. 7. Knee-joint structure; ligaments; 
patella and its function. 8. Ankle, number of bones, structure of, move- 
ments; liable to injury. 9. Foot, number of bones; instep; toes; compared 
with hand as to functions. 10. Joint defined; general classes of; classes of 
movable. 11. Ball-and-socket — examples of. 12. Hinge — motion, examples 



SUGGESTED POINTS FOR QUESTIONS. 45 

of. 13. Pivot — motion, examples of. 14. Mixed joints. 15. Sliding 

joints, characteristics. 16. Immovable joints, structure of, examples of 

sutures. 17. Cartilages of joints; synovial membrane and fluid — functions 
of. 18. Ligaments described; tendons; disposition of ligaments about 

joints. 19. Wonderful joint apparatus. 20. Coverings of the skeleton 

muscles, skin, hair, etc. 21. Health of bone — balance in processes; pri- 
mary requisites. 22. Proportions of constituents; preponderance of either 
constituents and effects; unimpaired digestion necessary; circulation normal; 
exercise to stimulate and strengthen. 23. Distortion from improper posture. 
24. Lateral curvature of spine; weakening of spinal muscles; permanent 
contraction; shortening of a leg. 25. Importance of balanced position; 
correction of curvature. 26. Distortion from dress; false notions; displace- 
ment of internal organs. 27. Impeded respiration and circulation. 28. Bone 
liable to disease. 29. Inflammation of periosteum, causes; felon, treatment 
of. 30. Ulceration and effects of; scraping of the bone. 31. Death of bone; 
natural removal of; removal by surgery. 32. Softening of the bones; " bow- 
legs;" rickets; "deficiencies to be supplied; mechanical appliances. 33. 
Sprains — nature and treatment of. 34. Dislocations — indications; reduc- 
tion. 35. Fractures — production, indications, treatment, process of heal- 
ing, caution in use. 36. " Bolting " of food; health of teeth important. 
37. Particles of food lodged in teeth, removal of; brushing and brush; 
dentifrice; tender gums; dentist's services; artificial teeth. 



4 6 



ACADEMIC PHYSIOLOGY. 




EXPLANATION. 
i, Extensors of the fore-arm, wrist, hand, 
etc. 2, flexors of the wrist, hand, etc. 3, 
biceps, bends the fore-arm upon the arm, 
etc. 4, deltoid, raises the arm and moves 
it forward and backward. 5, triceps, ex- 
tends the fore-arm, etc. 6,pectoralis major, 
draws the arm to the side and across the 
chest. 7, serratus magnus, raises the ribs 
in inspiration. 8, rectus ab dominate, exert 
an equable pressure upon the abdominal 
organs, keep the abdominal walls tense, etc. 

9, pronators, turn the fore-arm inwards. 

10, flexors, bend the wrist, hand, etc. 11 
tensor femor is, renders the connective tis- 
sue of the thigh tense and aids in moving 
the thigh outwards; 12, sartorius bends 
the leg upon the thigh and aids in crossing 
the legs; 13, group of abductor muscles. 
These draw the thighs outwards. 14, rectus 
femoris, one of the chief extensor muscles 
of the thigh. 15, tibialis anticus, bends the 
foot on the leg ; 16, group of muscles which 
extend the toes. 17, vastus externus, aids 
in extending the leg. 



Fig. 18. Front View of the Superficial Muscles. 



THE MUSCULAR SYSTEM. 



CHAPTER VI. 

THE MUSCLES. STRUCTURE, CLASSES, AND FUNCTIONS. 

1. Muscle. — To produce motion in the animal machine 
one particular substance is employed, and is so situated 
and arranged as to perform very conveniently all the 
duties required of it. It is called muscle, and it consti- 
tutes all those portions of the body commonly called 
flesh, as distinguished from fat, bone, sinew, etc. It is 
the red or lean part of meat, and forms a very large por- 
tion of the bulk of the animal body. 

2. Muscles are attached principally to the bones, and, 
possessing a high degree of contractility, they move the 
various parts of the body in the direction desired by 
the will. At least, this is the function of a great class of 
muscles called the voluntary muscles ; but there is also a 
class called involuntary, which act independently of the 
will, as those regulating the action of the heart and of 
the respiratory organs, etc. 

3. Structure of the Muscles. — The muscles generally lie 
just beneath the skin, and surround the bones. They 
serve to give much of that graceful contour which the 
body exhibits. 

47 




48 ACADEMIC PHYSIOLOGY. 

4. The muscles individually consist of bundles of fibres 
placed parallel to each other and bound up in a thin, 
strong casing ; and these fibres are, in turn, composed 
of smaller bundles, or fasciculi (Lat. fasciculus, a little 
bundle). These fasciculi are themselves composed of 

fibres enclosed by a delicate, 
structureless membrane, 
called the sdrcolemma (Gr. 
sarx, flesh ; and lemma, a 
husk). It is the contrac- 
tions of the separate fibres, 
all acting at the same in- 

Fig. 19. A small portion of muscle, con- Stant, that give to the mUS- 
sisting of larger and smaller Fasciculi. c 1g jj- g crreat Strength Kach 

explanation. muscle is distinct from 

A, natural size ; b, magnified five diameters. eyery ^j^ bdng endosed 

in its own sheath, and easily separable from other parts. 

5. When we consider that there are more than four 
hundred muscles in the human body, each named and 
each subserving some necessary purpose, we can realize 
how extensive a subject is anatomy, and how much 
application is required to obtain a knowledge of its 
details. 

6. Size, Shape, and Attachments. — Antagonists. — The mus- 
cles vary greatly in size, shape, and method of attachment 
to the bones and other parts. Some are long and thin, 
others broad and flat, some circular, and still others ser- 
rated or tooth-shaped. They are arranged in pairs, and, 
with few exceptions, each muscle has an antagonist, by 
the contraction of which motion in an opposite direction 
is produced. Thus as one muscle or set of muscles bends 
a limb, the opposite muscle or set extends or straightens 



THE MUSCULAR SYSTEM. 



49 



it ; and hence the former are called flexors, the latter 
extensors. 

7. For purposes of description each long muscle may 
be regarded as consisting of three parts, viz., the body, 
which is the middle portion, full and 

round, and the two extremities, which 
taper gradually and gracefully. The 
voluntary muscles are connected with 
the bones generally, but some are at- 
tached to cartilages, to the skin, and 
to other structures. Involuntary mus- 
cles are not generally attached to the 
bones, but form part of the walls *of in- 
ternal organs, as in the heart, blood- 
vessels, stomach, and intestines. 

8. Muscles are attached to bones 
sometimes directly, but more commonly 
by means of tendons or sinews, which 
are strong, glistening bands or cords 
of fibrous tissue, continuous with the 
muscle at its point of attachment with 
the bone. The tendons sometimes ex- 
tend a considerable distance to parts 
remote from the moving muscle, and 
run through grooves before becoming 
attached. In this way they act as pul- 
leys, and give motion in a direction 
different from that they would if their 
course was direct, as in the superior oblique muscle of 
the eye, etc. 

9. By a wise provision, in places where the tendons 
would play over hard surfaces, there are interposed little 




Fig. 20. Biceps muscle 
of the arm. 

EXPLANATION. 

a, body of the muscle. 

b, b, superior tendons. 

c, inferior tendons. 



5<D ACADEMIC PHYSIOLOGY. 

sacs, called bursa, which contain fluid and act as cush- 
ions. 

10. The point from which a muscle acts is called the 
point of origin, and the movable end (that upon which it 
acts) is called the point of insertion. 

11. Tendons. — The tendons, although very strong, are 
slender, and hence conduce greatly to the symmetry of 
parts that would otherwise be bulky and ungraceful. If 
the great muscles of the arm were prolonged to the wrist, 
or those of the leg to the ankle, the limbs would lack 
beauty of outline. These muscles terminate in long, slen- 
der tendons, which, commencing above the wrist or above 
the ankle, pass over these joints to the foot and toes, or 
hand and fingers, respectively. When the foot is stretched 
out, or when the wrist is not bent, the muscles and their 
tendons form nearly straight lines ; but when either joint 
is bent, the tendons curve, as it were, around a pulley. 
When muscles act very powerfully, the tendons would be 
forced up from their places, in order to fall into straight 
line with the muscles, were they not bound down by 
strong bands, called ligaments, running across them. At 
the back of the calf of the leg certain muscles are con- 
nected with the heel by the tendon of Achilles, the lar- 
gest and strongest in the body. 1 

12. Circular Muscles, etc. — A form of muscle quite com- 
mon is that of the ring or circle. Muscles of this form 
close or constrict natural openings of the body, as the 
mouth, eye, and those leading into and out of- the stom- 
ach, etc. The most beautiful and delicate of all is the 
muscle which forms the iris of the eye. These ring- 

1 In Grecian fiction this tendon is represented to have been the only vulnerable part 
of the body of Achilles, and hence its name. 



THE MUSCULAR SYSTEM. 5 1 

like muscles are technically named annular^ orbicular, or 
sph inctt r m uscles. 

13. By means of the circular and other muscles of the 
face, the various expressions of the emotions are effected ; 
and hence they constitute what are termed the muscles of 
expression. 

14. Muscles are attached to the skin and move it over 
the tissues beneath it, as is seen in wrinkling the fore- 
head or moving the scalp. In the lower animals this is 
more common, enabling them to give quick motion to the 
skin and thus rid themselves of troublesome insects. 

15. Contractility of Muscles. — The property of contrac- 
tility, under certain exciting causes, distinguishes muscles 
from other tissues of the body. 

In contraction the fibres shorten, and the apparent gain 
in the bulk of the muscle is at the expense of its length. 
Under natural conditions this contraction is accomplished 
in obedience to the stimulus imparted by the nerves which 
supply the muscle. This is strictly true in regard to the 
muscles called skeletal muscles, those which move the 
limbs or other parts of the body and cause change of its 
position. These movements can be accomplished norm- 
ally only when the nerves themselves remain in communi- 
cation with the brain and spinal cord. 

16. Another condition exists in muscle, however, which 
is termed its irritability. This may be exhibited by ap- 
plying some stimulus to the muscle, as by pinching, or 
applying a hot iron to it, or by a current of electricity ; 
contractions may be thus produced independently of the 
nerve. But the same results may also be attained by ap- 
plying a stimulus to the nerve. It, also, is irritable ; and 
although there is no change in form in the nerve, move- 



52 ACADEMIC PHYSIOLOGY. 

ments are set up and communicated to the muscle, which 
contracts, as in the former case. These phenomena in 
the nerves are called nervous impulses. 

17. It is now conceded by physiologists that muscular 
and nervous irritability are separate from each other, as 
shown by the fact that certain things that act as stimuli 
to the muscles will not so act upon the nerves, and vice 
versa. 

18. Velocity of Contraction. — Elaborate instruments have 
been invented and are used to measure muscular move- 
ments, — the velocity of nervous impulse, etc. Some of 
the facts ascertained by these means are as follows, viz. : 

a. That the commencement of molecular changes in a 
muscle stimulated to contraction by electricity occupies 
about t 1q of a second. 

b. That the shortening of the fibres of the muscle oc- 
cupies about y^y of a second. 

c. That the return of a muscle to its former length 
occupies about T ^ of a second. 

19. The Unstriated Muscles. — This class of muscles differs 
from those we have been considering in that they consist 
of flattened bands made up of bundles of fibres ; again, 
they have no surrounding membrane or sheath, and do 
not present under the microscope the appearance of 
strings of beads, and hence are called unstriated. 

20. The unstriated muscles belong principally to the 
viscera, or internal organs. They are found also in the 
skin at the bases of the papillce, and their contraction 
causes the appearance of the skin sometimes seen, and 
commonly called " goose skin." 

21. While the general muscles of the frame are seen to 
be connected with and regulated by the nerves originating 



THE MUSCULAR SYSTEM. 53 

from the brain and the spinal cord, those of the internal 
organs seem to be under the control of the sympathetic 
nervous system. 

22. The phenomena of both classes of muscles are very 
similar as regards contractility, the same stimuli produ- 
cing like results in each case. The wave-like impulse 
observable in a marked degree in the muscles of the 
intestines is called peristaltic motion. 

23. The continued action of the muscles of the heart 
under the various stimuli peculiar to it will be studied 
later. Its rhythmic action is the result of various forces, 
the ultimate result of which is to produce regular and 
continued contractions and expansions. 

24. Arrangement of Fat. — Fat ordinarily constitutes about 
"gLj part of the weight of the body. It is found under the 
skin, between the muscles and about the internal organs. 
Its various uses are to maintain bodily warmth, to fill up 
inequalities and thus give symmetry to the form, and to 
act as cushions to various muscles, joints, etc. 



CHAPTER VII. 

BRIEF DESCRIPTIONS OF IMPORTANT MUSCLES. 

1. Elaborate descriptions of the muscles are impossi- 
ble and undesirable in a volume of this kind, and therefore 
brief mention is made of those of the several divisions of 
the body. 

2. Muscles of the Head and Face. — The muscles of the head 



54 



ACADEMIC PHYSIOLOGY. 



and face, by their varied motions and degrees of develop- 
ment, give different expression to each individual, and 
make it impossible for any two persons to look exactly 
alike. 




A closes the eye ; B raises the eyebrows, and wrinkles the forehead ; C raises the lower 
jaw ; D closes the lips ; E compresses the wings of the nose ; F draws the corner of the mouth 
downward. Each muscle has a name given to it because of the work it performs, its shape or 



3. One large muscle, which covers the entire front and 
top of the skull, moves the scalp and throws the skin of 
the forehead into transverse wrinkles, while two small 



THE MUSCULAR SYSTEM. 55 

muscles, just above the inner angles of the eyes, draw 
the eyebrows downward and inward, and produce vertical 
wrinkles in the forehead. One circular muscle forms the 
eyelid and closes it to protect the eye ; another muscle 
raises the upper lid, and six muscles are employed in giving 
the ball of the eye its various motions. A ring-like mus- 
cle surrounds the mouth and closes the lips tightly, as in 
puckering the lips to whistle. Other small muscles raise 
the upper lip, draw the angles of the mouth upward and 
downward, depress the lower lip, elevate the sides of the 
nose, move the lower jaw (powerful muscles in this in- 
stance), and produce the several movements of the face, 
the rapid changes which are called facial expression. 

4. Muscles of the Neck. — -The muscles of the neck are 
numerous and complicated. Those in front are rendered 
more complicated by the position of the bone near the 
root of the tongue (the hyoid bone), to which several of 
them are attached. These muscles extend upward to the 
head, but some of them attach themselves to the hyoid 
bone, while smaller muscles extend from that bone up- 
ward. The muscles of the front of the neck bend the 
head forward, draw the lower jaw down and thus open the 
mouth, aid in moving the organs of speech, and assist in 
swallowing. The muscles of the sides of the neck bend 
the head to the side when those on one side act alone, 
and rotate the head on the spine. When those of both 
sides act together, they aid in keeping the head erect. 
The muscles in the back of the neck draw the head back- 
ward, raise the shoulders, and also aid in holding the head 
erect. 

5. Muscles of the Trunk. — The muscles of the trunk are 
those that cover the front, sides, and back of the thorax 



ACADEMIC PHYSIOLOGY. 




or chest, and those that 
form the walls of the ab- 
domen. There are also 
some internal muscles 
that properly belong to 
the trunk. 

6. The muscles of the 
breast cover the upper 
and front part of the 

EXPLANATION. 

- i, extensors of the hand ; 2, flexors of 
the hand, wrist, and fingers; 3, biceps, 
bends the fore-arm; 4, deltoid, raises 
the arm and moves it backwards and 

2 forwards; 5, triceps, extends the fore- 
arm ; 6, trapezius, moves the head 
backward, sideways, etc., and raises the 
shoulder; 7, latissimus dorsi, assist in 
respiration, aid in lowering the arm 
when raised, etc. ; 8, gluteus maxi- 
mus, raises the thigh backward and out- 
ward ; 9, vastus externus, aids in extend- 
ing the leg; 10, biceps cruris, aids in 
bending the leg on the thigh ; 11, gas- 
trocnemius, forms the calf of the leg, 
and aids in extending the foot; 12, flex- 
ors, of the foot ; 13, tendo Achilles, at- 
tached to the heel and to 11. 

chest. The pectoralis 
major or great muscle of 
the breast has an exten- 
sive attachment to the 
ribs, breast-bone, and 
collar-bone, and is also 
attached to the upper 
part of the humerus or 
arm-bone. It draws the 



Fig. 22. Back View of the Superficial Muscles. 



THE MUSCULAR SYSTEM. 57 

arm forward, across the body, toward the opposite side ; 
and when it acts with the great muscle of the back, the 
arm is drawn close to the side. The muscles on the 
sides aid in moving the ribs during breathing. 

7. The muscles of the back are very numerous from the 
fact that many and varied movements are required at this 
point. They all arise from the bones of the spinal column, 
and aid in keeping the trunk in the erect position. Some 
of them give the backward motions to the head, and others 
draw the shoulder-blades back towards the spine. The 
latissimus dorsi or largest muscle of the back is inserted 
into the humerus or arm-bone near the point where the 
great muscle of the breast is also inserted. When it acts 
alone, it draws the arm backward ; but when it acts with 
the breast muscle, it helps to draw the arm close to the side. 

8. The abdominal muscles form the movable walls of the 
abdomen ; acting together, they bend the trunk forward, 
and they also aid in the movements of breathing. At the 
lower part of these muscles, just above the long rim of 
the pelvis, are two weak points in the abdominal walls, 
and they often give way and allow a portion of the intes- 
tines to come through, thus constituting what is called 
hernia or rupture. 

9. The spaces between the ribs are filled by muscles 
which raise the ribs in order to make room for the inflation 
of the lungs in breathing. These are called intercostal 
muscles (Lat. inter, between ; and costa, a rib). 

10. The diaphragm (Gr. phragma, fence) is the broad, 
convex-concave muscle, situated in the interior of the 
trunk, which separates the cavity of the thorax or chest 
from that of the abdomen. It rises and falls during 
breathing, in which it plays an important part. 



58 



ACADEMIC PHYSIOLOGY. 



11. Other muscles are situated in the cavity formed by 
the bones of the hips, and pass outward and are inserted 
into the upper part of the femur or thigh-bone. They 
assist in rotating the whole leg 
so as to turn the toes outward, 
and in drawing the thigh upward 
in the direction of the abdomen. 

12. Muscles of the Upper Extremi- 
ties. — The muscles surrounding 
the shoulder, together with others 
from the trunk, previously de- 
scribed, are attached to the arm 
(or upper-arm, as it is sometimes 
called) and constitute its motors. 
The triangular muscle called the 
deltoid (from its resemblance in 
form to the Greek letter delta), 
situated at the top of the shoulder, 
raises the arm to the side of the 
head, while smaller muscles acting 
with the great muscles of the 
breast and the back draw it down 
to the side of the body. Other 
movements of the arm caused by 
these great muscles have been 
stated previously. 

13. Three muscles occupy the 
front part of the arm. The chief 
one of these is called the biceps 
muscle (Lat. ai, two ; and caput, a 

head), because at its upper extremity it has two heads 
with separate tendons. These muscles draw up the fore- 




Fig. 23 



The Cavities of the Trunk. 

EXPLANATION. 

i, bodies of the vertebras ; 2, 
spinous processes of the vertebra; ; 
3, spinal canai ; 4, breast-bone; 5, 
diaphragm ; 6, thorax ; 7, abdo- 
men. 



THE MUSCULAR SYSTEM. 



59 



arm as in the attitude of striking, while the large mus- 
cle on the back of the arm, called the triceps or three- 



EX PLAN ATI ON. 

/, the muscle that straightens the 
fingers. 

k, the muscle that straightens the 
little finger. 

z, the muscle that assists in straight- 
ening the wrist. 

/, the muscle that assists in extending 
the fore-arm. 

d, the muscle to extend the second 
bone of the thumb outward. 

e, the muscle to extend the fore- 
finger. 

k, the muscle to draw the little finger 
outward. 

m, the muscle to roll or turn the 
fore-arm, and turn the hand. 

g, the ligament which binds down 
the muscles at the wrist. 



I^&I 



Fig. 24. 



EXPLANATION. 

a, the muscle to turn the hand inward. 

b, the muscle to bend the wrist. 

c, d, the muscles to bend the hand. 
e, the muscle to assist in bending the 

hand. 
g, the muscle to bend the thumb. 



Fig. 25. 



headed muscle, extends or straightens the arm upon the 
forearm, thus acting as an antagonist. 



60 ACADEMIC PHYSIOLOGY. 

14. The muscles on the front of the forearm bend the 
whole hand forward at the wrist, and also bend the fingers 
so as to form the clenched hand or fist. The action of 
these is antagonized by the muscles of the back of the 
forearm, which straighten the wrist and fingers, and also 
carry the whole hand backward at the wrist. A set of 
muscles on the thumb side of the forearm draw the hand 
toward that side, and also rotate it outward so that it 
rests on its back, the palm turned upward. Another set, 
situated on the side corresponding with the little finger, 
draw the hand toward that side, and rotate it inward, so 
that the palm is turned downward. When the hand rests 
on its back, it is said to be supine, and the muscles giving 
the motion are called supinators ; those that turn the 
palm downward are called pronators, and the hand is then 
spoken of as being in the prone position. 

15. Muscles of the Lower Extremities. — The muscles which 
move the thigh are short, thick, and powerful. They form 
the fleshy mass that covers the back of the hip-bones, 
and arise from the bones of the pelvis and lower part of 
the backbone. 

16. The four large and long muscles situated in front 
of the femur or thigh-bone straighten the leg upon the 
thigh after the knee has been bent. They arise from the 
pelvis and thigh-bone, and unite below in a broad tendon 
in the centre of which the patella or knee-cap is situated. 
Below the knee-cap this tendon contracts, and is called the 
ligament of the patella, and is attached to the upper part 
of the tibia or shin-bone. A large biceps muscle back 
of the thigh-bone draws the leg up backward, so as to 
bend the knee ; and a set of muscles on the inner sides 
of the thighs draw the legs together. 



THE MUSCULAR SYSTEM. 



17. On the front of the leg are several muscles called 
extensors, the tendons of which extend to the ankle and 
to the bones of the toes. These straighten the toes and 
draw the foot up in front toward the leg. The muscles 




In this figure the muscles of the lower part of the leg and of the foot are represented. 
Those used in extending the toes, and bending the foot upward, are situated in front of the 
leg and upper part of the foot ; while those that bend the foot downward, and bend the toes, 
are located at the back of the leg and on the sole of the foot. These muscles are attached to 
the toes by round, cord-like tendons, that may be plainly felt, and their form seen, when the 
toes are extended or drawn upward. 

a, the broad ligament that binds down the muscles of the ankle. 

b, the tendon of Achilles, at the back of the ankle, which extends from the muscle of the 
calf to the back of the heel. This is the strongest tendon of the body : it raises the heel. 

c, muscles which turn the foot outward. 

d, tendons of muscles that extend the toes. 

e, tendon of muscle that extends the great toe, and separates it from the next. 

f, muscle of the calf of the leg. 

g, muscles that bend the ankle, and pull the foot toward the shin. 

on the back of the leg, the tendons of which also extend 
to the ankle and foot, flex or bend the foot and toes, and 
draw up the heel so that the toes are pointed downwards. 
These latter muscles are called flexors. A similar arrange- 
ment of extensor and flexor muscles and their tendons 
exists in the forearm and hand, as we have seen. 



62 



ACADEMIC PHYSIOLOGY. 



18. Muscles attached to Levers. — The great majority of 
the muscles in the body are attached to distinct levers 
formed by the bones. It is one or other of the extremities 




Fig. 27. 

The Bones of the Upper Extremity and the Biceps and 
Triceps Muscles. 



EXPLANATION. 

In this figure the biceps 
muscle is shown at C, and the 
two tendons which attach it 
to the shoulder are seen at G, 
the point of origin. 

The attachment of the mus- 
cle to the radius is shown at 
A, the point of insertion. 

The triceps muscle is repre- 
sented at F, and the tendon 
by which it is attached to the 
radius is shown at B. These 
two muscles are antagonistic 
•muscles. 



of a bone which plays the part of a fulcrum when the bone 
is in use as a lever, the muscle being the power, and the 
resistance to be overcome the weight. 



CHAPTER VIII. 



PHYSIOLOGY AND HYGIENE OF MUSCULAR EXERCISE. 



1. Object of Exercise. — We shall here speak of proper 
muscular exercise as being one of the chief agents in the 
maintenance of health, and in its restoration when im- 
paired. Primarily, exercise gives health, strength, and 
tone to the muscular system ; and secondarily, by means 
of its effect on the muscles it confers health upon all the 
other tissues. Grace and dexterity of movement are the 
desirable subordinate qualities to be attained. 



THE MUSCULAR SYSTEM. 63 

2. Influence of Exercise. — We have learned that the mus- 
cles are called into action by nervous impulse ; and it 
should be remembered that in exercise " not only the 
muscle, but almost the whole nervous system labors," and 
that in muscular exercise there is just as truly a putting 
forth of nervous energy as there is in mental efforts. 

It is next desirable to get clear ideas of the influence 
of exercise, and to learn how it can do good. The blood- 
vessels permeate the muscles which they supply with 
blood, and are covered and protected by adjacent over- 
lapping muscles. In consequence of their location, the 
blood-vessels are compressed and their contents propelled 
by the contraction and pressure of the muscles. But the 
increased activity of the circulation thus induced by mus- 
cular action is not confined to the muscles. The action of 
the heart is hastened, the blood passes through the lungs 
more rapidly and in larger quantities, and the respiratory 
and perspiratory organs are urged to quickened action, in 
order to purify the blood with sufficient rapidity. The 
influence of increased circulation is felt in all the organs. 
Increased activity occasions combustion of material and 
the elimination of waste products ; and hence, to supply 
the demand for quantity of blood, the appetite is excited, 
more food is eaten, and the digestive organs participate in 
the general activity. It will thus be seen that exercise is 
a renovator of the body, that almost every function is 
impelled to increased activity by it, and that the whole 
system receives a healthful impulse. In short, muscular 
exercise influences so greatly the two vital processes — 
destruction and renewal of tissues — that it must be taken 
into chief consideration by him who would have good 
health and long life. 



64 ACADEMIC PHYSIOLOGY. 

3. To the young, exercise is especially important, since 
it not only stimulates the functions to which allusion 
has been made, but also contributes to development and 
largely determines the size, strength, and functions of the 
whole body. 

4. Muscular Strength. — Difference in physical strength 
is due mainly to the non-employment of the muscular 
system, in one case, and to its regular and continued exer- 
cise in the other. Many who lead active and laborious 
lives have vigorous health, and muscles that will endure 
an almost incredible amount of labor ; others, equally 
strong in early age, who lead sedentary and inactive pur- 
suits, are subject to a variety of ailments and have but 
little muscular strength. 

5. By a regular and moderate exercise of individual 
muscles they will increase both in size and strength. 
When kept in action more blood is sent to them, and 
consequently a greater deposition of muscle-making sub- 
stance takes place. On the other hand, if muscles are 
unused, atrophy or waste takes place, and they become 
weak and flabby. 

6. Amount of Exercise. — To increase the size and strength 
of a muscle, its exercise must be uniform and not exces- 
sive. The amount of exercise must be determined by the 
present strength of the individual, and it should be dis- 
continued at the first sign of fatigue. The intervals of 
relaxation should be frequent in order to give the muscle 
and its nerve opportunity to recruit their powers. If the 
occurrence of fatigue is not regarded and the muscles are 
still continued in action, their energies may become so 
much exhausted as to permanently impair their contrac- 
tile power. 



THE MUSCULAR SYSTEM. 65 

7. Proper and Improper Exercise. — Whatever the kind of 
exercise, there are certain rules which every young per- 
son should be taught to regard. In youth, bones, muscles, 
and nerves are immature ; they gradually attain their bulk, 
firmness, and approximate perfection. They require gen- 
tle treatment. Violent exercise is quite out of place at 
this period of life, and what should be aimed at is slow 
exercise with frequent intervals of rest. The object of 
exercise in the gymnasium or elsewhere should not, pri- 
marily, be to attain dexterity, though this naturally follows 
after a time, but to train and develop the muscles. Vio- 
lent exertions, in the attempt to accomplish difficult or 
rapid feats, produce exhaustion and greatly overstrain the 
muscles. Whether a particular gymnastic feat is accom- 
plished or not is a matter of but little consequence ; the 
important matter is that the muscles shall have sufficient 
exercise and shall not be overstrained. Muscular exercise 
is potent for evil as well as for good, and when excessive 
is certainly injurious. It should begin moderately and be 
gradually increased. 

8. Preternatural Muscular Development. — Increase of the 
bulk of the muscles means also increase in the quantity 
of blood and of the space to be travelled by it. Such 
increase of blood and territory demands augmentation of 
power to drive the vital fluid through the system, and to 
get rid of the gases of the blood. Only to a limited ex- 
tent can the heart accommodate these increased demands, 
and there is no reason to believe that the aerating surface 
of the lungs can be largely increased. But a preter- 
natural development of muscle requires a preternatural 
amount of work of the heart and lungs. It is well known 
that a large proportion of professional athletes die early of 



66 ACADEMIC PHYSIOLOGY. 

lung and heart diseases ; and one of the reasons why men 
whose muscular systems have been preternaturally de- 
veloped so often die of lung and heart diseases is to be 
found in the fact that these organs are, in such people, 
habitually overworked in supplying the over-developed 
muscles. 

9. It is very important to remember that an over-devel- 
opment of the muscles is possible, and that there is dan- 
ger in a system of training in which the muscles are so 
cultivated as to be especially able for great, sudden efforts. 
Great momentary muscular strength and great endurance 
under continued exertion are by no means synonymous. 
They may be united in the same person, but it is possible 
to possess the former and not the latter. It is equally 
important to remember that moderate, regular, protracted 
muscular work is the best cultivator of endurance, and 
that endurance is to be chiefly sought in cultivating the 
muscles. 

10. Pure Air and Sunlight for Exercise. — It has already been 
stated that exercise stimulates the circulation of the blood 
and that the quantity of that fluid passing through the 
lungs and demanding aeration is greatly increased under 
its influence. The air breathed, at that time especially, 
should contain its proper proportion of oxygen, and hence 
exercise should be conducted in the open air or in freely 
ventilated rooms. Under the most favorable conditions, 
the hastened respiration indicates the demand for oxygen 
in increased quantities. If the air breathed is impure 

1 Even the training undergone for the performance of great physical feats exhausts 
life force in the long run. Athletic sports pushed to extreme produce bad results, and 
they must be so pushed to win renown. Dissipation has nothing to do with many 
instances of lives thus shortened. In either case the penalty is exacted. 



THE MUSCULAR SYSTEM. 6/ 

from a mixture of unwholesome gases, " or if its proper 
proportion of oxygen be reduced by having been previ- 
ously breathed, the good effect of exercise on the vital 
force is lost, and even a positive injury may be the re- 
sult." Winship, the famous athlete, when in his best 
condition often fainted in a close room. Under the most 
favorable circumstances his heart and lungs had as much 
as they could do to meet the needs of his system, so that 
when compelled to work in vitiated air they were unable 
to meet the requirements. 

11. Sunlight exerts a marked influence upon both vege- 
table and animal life. The plant hidden from the light 
loses its color and vigor, and animals deprived of it also 
have feebler vitality. The results of repeated experi- 
ments would appear to prove conclusively that labor can 
be borne with less fatigue in the sunshine than in the 
shade, the temperature of the air being the same in both 
instances. Pure air, sunlight, and well-regulated exercise 
are the hand-maidens of health. 

12. Modes of Exercise. — That form of exercise is best 
which brings into moderate play the greatest possible 
number of muscles, and hence the exercise of one set of 
muscles should not be allowed to exclude others. Gym- 
nasia are equipped with apparatus adapted to this end ; 
but where such means are not available, much can be 
accomplished by using the simple means within reach. 
Those employed in, sedentary pursuits should regularly 
devote some time each day to an amount of exercise 
within the limits of prudence, the amount to be deter- 
mined by the strength of the individual, and, as said 
before, the exercise should be discontinued at the first 
sign of fatigue. 



68 ACADEMIC PHYSIOLOGY. 

13. Running is an excellent exercise, bringing muscles 
into play more vigorously than walking does ; but there 
is probably no other form of exercise that requires such 
cautious, gradual training. In practising running, we 
should bear in mind the fact that in all strong, athletic 
exercises we should be satisfied with gradually attained 
powers. Both lungs and heart are sometimes injured by 
the strain put upon them by undue exercise in running. 
Breathlessness, strong beating of the heart, and soreness 
of muscle lasting after exercise, show that it has been too 
prolonged, or too rapid. 

14. Walking is, in many respects, a good exercise. In 
walking, the muscles chiefly exercised are those of the 
legs ; but those of the arms and trunk participate to a 
certain extent, and the exercise which the latter obtain 
increases the breathing power of the lungs. The respi- 
ration is quickened, a greatly increased amount of air is 
inhaled, and a correspondingly large quantity of carbonic 
acid exhaled. This, while true of various modes of exer- 
cise, is especially beneficial in walking in the open air. 
Investigations show that the quantity of air inspired by 
a person when walking at the rate of six miles per hour 
is seven times the quantity inspired by the same individual 
when quiescent, or in a recumbent position. But walking 
does not sufficiently exercise the muscles of the upper 
portions of the body, and hence is not to be depended on 
for all purposes of exercise. 

15. Swimming brings into action almost all of the 
muscles of the trunk and limbs, and is therefore an excel- 
lent mode of exercise. The effects of bathing will be 
presented in another chapter. 

16. Rowing also is an excellent exercise, bringing into 



THE MUSCULAR SYSTEM. 69 

play principally the muscles of the shoulders, arms, and 
loins. When much practised, rowing may cause a ten- 
dency to round shoulders and hollow chests unless care 
is taken to bring the trunk to an erect position. Here, 
again, due regard should be given the rule that the exer- 
cise of one set of muscles must not be allowed to exclude 
others, and hence rowing should not have " the lion's 
share" among the forms of exercise. 

17. Calisthenics is a term formed from two Greek 
words, — kalos, graceful, and sthenos, strength, — and, as 
now used, signifies the exercise of the body for the pro- 
motion of strength and grace of movement. In this 
sense it may be made to include all exercises with Indian 
clubs, dumb-bells, etc. One of the most important things 
to be remembered in all exercise is, that it is the motion 
more than the weight of implements that yields benefit ; 
so that in the beginning, at least, light dumb-bells, etc., 
should be employed. Calisthenics or light gymnastics 
may be so varied as to call into play all the voluntary 
muscles. 

18. Fencing, tennis, riding, driving, "wheeling" in its 
various forms, are exercises which include sociability and 
enjoyment, and therefore have a great advantage over 
those of a grave and solitary nature. All outdoor exer- 
cises except the roughest and most dangerous are to be 
highly recommended, as they combine all the useful accom- 
paniments of fresh air, high spirits, and physical effort. 
In fact, there is nothing that comes nearer than judicious 
exercise to being a real " cure all." 

19. Artificial Props. — Tight Clothing. We have referred to 
the muscles attached to the spine and employed in keep- 
ing the trunk erect. The course already alluded to as 



yO ACADEMIC PHYSIOLOGY. 

the proper one for increasing the power of muscles applies 
to these, and is especially necessary to them. Nature is 
continually endeavoring to exercise economy, and- when 
organs are not employed in fulfilling the purposes for 
which they were intended, she curtails to the utmost 
her supplies of nutriment. " Thus it is that the unused 
brain becomes dull and stupid, and the ligated artery is 
absorbed ; " and thus it is, also, that the unused muscle 
dwindles from inaction and consequent lack of nutrition, 
and becomes totally unprepared for any extra demands 
which may be made upon it. 

20. By a large proportion of the female sex, and by 
many of the other, these natural laws are neglected or 
repudiated. Not only are the muscles of the spine not 
educated as they should be, but by many are not allowed 
to perform the work nature designed. By the strong 
constriction of tight clothing and tight lacing it is at- 
tempted to keep the spine erect with but little aid of the 
muscles ; and thus a severe restraint is put upon them by 
a forcible compression which interferes with their con- 
traction and also impedes the circulation of the blood in 
them. Enforced inaction and deficient circulation dwarf 
and weaken the muscles, and they become unable to 
perform their natural and rightful function of keep- 
ing the spine erect and chest expanded. To restore 
the strength of such deteriorated muscles constric- 
tion and artificial props must be removed, and the 
muscles allowed unconstrained exercise, their natural 
function. 

The muscles of the back are adequate to keep the spine 
erect and the shoulders in proper position, if their strength 
is cultivated by proper means in early age. Habits of 



THE MUSCULAR SYSTEM. 7 1 

walking and sitting erect should be inculcated, but not on 
any occasion to an extent that causes fatigue. 

21. " Girls and young women," remarks an eminent 
physician, " ought to be physically trained as carefully as 
are boys and young men ; while nature has not designed 
that the sexes shall be possessed of equal strength, the 
female should have strong muscles, lung space, and all 
the benefits to be derived from proper bodily exercise. In 
some schools this matter is receiving enlightened atten- 
tion," etc. But it is absurd to require or expect a free 
exercise of the body, encased in tightly fitting, muscle- 
constricting clothing ; the whole body must be free to ex- 
pand and bend ; otherwise the exertion soon becomes 
painful and worse than useless. Besides, as has been well 
said, " The processes of life conducted by the vital organs 
of the body are too essential for us to trespass upon 
them by any of those external appliances which tend 
to compress them or interfere with natural freedom of 
motion." 

22. Alcohol, Tobacco, and the Muscles. — The injurious 
effects of alcoholic drink and tobacco on digestion, the 
blood and its circulation, and on the nervous system are 
fully stated elsewhere. As the health of the muscles is 
intimately related to these, it is therefore inevitable that 
they must participate in and be impaired by influences 
which are so deleterious to digestion, blood-making, and 
circulation, and nervous health. Alcohol paralyzes nerve- 
force, and thus robs muscle of its natural stimulus ; it 
frequently causes fatty degeneration, not only of voluntary 
muscles, but those of the heart and arteries, thus chan- 
ging the lean muscle into fat and destroying its structure. 
Tobacco attacks the nerves and causes unsteadiness of 



7 2 ACADEMIC PHYSIOLOGY. 

nerve and muscular action. Muscle becomes exhausted 
sooner when alcoholic drink has been taken, and athletes 
avoid it when preparing for feats of strength or endur- 
ance. Human experience proves that alcohol and tobacco 
are enemies of the muscles. 



Suggested Points for Questions. 

Chapter VI. — i. The production of motion — muscle. 2. Attachments 
and contractility; voluntary and involuntary. 3. Location, bodily contour. 
4. Fibres, fasciculi, sheath, simultaneous contraction of fibres. 5. Number 
of muscles. 6. Size, shape, antagonists, flexors, and extensors. 7. Three 
parts of a long muscle; attachments of voluntary and of involuntary. 8. 
Method of attachment to bones — tendons, pulleys. 9. Bursse. 10. Point 
of origin and insertion. 11. Tendons, form, symmetry, functions; liga- 
ments—uses. 12. Circular muscles, offices and examples of. 13. Muscles 
of expression. 14. Muscles of the skin. 15. Muscular contractility, how 
accomplished. 16. Muscular irritability; stimulus applied to nerve. 17. 
Nervous and muscular irritability distinct. 18. Velocity of contraction — 
commencement, shortening, return. 19. Unstriated muscles — absence of 
sheath, etc. 20. Muscles of viscera, etc., unstriated. 21. Muscles regulated 
and controlled by nerves — sympathetic nerves and internal muscles. 22. 
Similar phenomena of both classes; peristaltic motion. 23. Continued action 
of heart-rhythmic action. 24. Arrangement of fat — offices of fat. 

Chap. VII. — 1. Elaborate descriptions undesirable. 2. Muscles of head 
and face — expression; no two exactly alike. 3. Principal muscles of head 
and face and their functions — facial expression. 4. Muscles of the neck; 
attachments to hyoid bone; offices of the principal ones — front, sides, and 
back of neck. 5. Muscles of trunk, cover what, etc. 6. Muscles of breast — 
pectoralis major, location and functions; muscles of the sides — functions. 
7. Muscles of back — number, origination, principal functions; latissimus 
dorsi, structure and office. 8. Abdominal muscles — functions; weak points 
of abdomen — hernia. 97 Intercostal muscles — functions. 10. Diaphragm 
— location, form, office. 1 1. Muscles of hip-cavity — functions, rotation of 
leg, etc. 12. Muscles of upper extremities — shoulder and arm; deltoid and 



SUGGESTED POINTS FOR QUESTIONS. 73 

its office; smaller muscles of breast and back co-operate. 13. Three muscles 
of arm, functions; biceps^ triceps — antagonists. 14. Office of front forearm 
muscles; of back of forearm; of thum-side; of little-finger side; supinators, 
pronators. 15. Muscles of lower extremities — of the thigh and hips, origi- 
nation in pelvis and spine — nature of. 16. Muscles of front of thigh-bone — 
offices; tendon of the patella, ligament and attachment; biceps of back of the 
thigh — function; muscles of inner sides of thigh — functions. 17. Muscles 
of front of leg — extensors — functions, tendons, attachments; of the back of 
the leg, ditto. 18. Muscles attached to levers — fulcrum, power, weight. 

Chap. VIII. — 1. Muscular exercise a chief agent of health; primarily 
and secondarily considered; grace and dexterity. 2. Influence of exercise — 
nervous impulse and labor; blood-vessels compressed and blood propelled by 
contraction; action of heart hastened; circulation quickened in lungs, etc.; 
increased combustion and elimination; increased appetite and digestion; exer- 
cise a renovator; healthful impulse; influences two vital processes. 3. 
Exercise important to the young — development. 4. Muscular strength — 
difference due to what; activity and labor; sedentary and inactive — con- 
trast. 5. Regular and moderate exercise — effect; atrophy or waste — inac- 
tivity. 6. Amount of exercise — uniform and not excessive; amount deter- 
mined by present strength; intervals; occurrence of fatigue to be regarded; 
exhaustion. 7. Rules for exercise; gentle treatment of immature muscles, 
etc.; violent exercise; primary object of exercise — dexterity or develop- 
ment; sufficient but not over-straining; moderation. 8. Over-development 
of muscle and its effects; increased demand on heart and lungs; athletes and 
length of life — reasons. 9. Danger of over-development; strength and 
endurance; cultivation of endurance chiefly important. 10. Pure air sun- 
light for exercise — reasons; increased demand for oxygen; Winship. 11. 
Sunlight — influence of, on plants and animals; labor in sunshine and shade; 
the hand-maids of health. 12. Modes of exercise, characteristics of each; 
benefits to be derived; best form of exercise — greatest possible number of 
muscles. 13. Running. 14. Walking. 15. Swimming. 16. Rowing. 17. 
Calisthenics. 18. Fencing, tennis, riding, driving, "wheeling." 19. 
Tight clothing — constriction interferes with exercise and development. 20. 
Natural laws neglected — muscles not educated but hampered; attempt to 
keep spine erect by tight lacing — effect on the muscles; removal of props; 
muscle adequate to keep spine erect, etc.; habits of walking, sitting, etc. 21. 
Physical training of girls and young women — strong muscles, lung space; 
no free exercise in tight clothing of trunk and limbs; trespass upon the vital 
processes by compression. 22. Alcohol, tobacco, and the muscles. 



74 



ACADEMIC PHYSIOLOGY 




Fig. 28. General view of the Circulatory System, showing the arrangement of the heart 
and the larger blood vessels. 

EXPLANATION. 
h, the heart. The arrows indicate the direction of the circulation. 



THE BLOOD AND ITS CIRCULATION. 



CHAPTER IX. 

THE BLOOD ) ITS COMPOSITION, PROPERTIES, ETC. 

1. The Vital Fluid. — When the surface of the skin is 
pricked, even slightly, immediately a minute drop of red 
fluid is seen, proving that even up to the very limiting 
bound of the body the sea of life flows a never-ceasing 
tide, laving, irrigating, and nourishing every tissue. 

2. This fluid, the blood, as it exists normally in the 
body, consists of the plasma} an almost colorless fluid, 
holding in suspension the red and the white corpuscles, 
which are cellular bodies, differing in size and con- 
stituents. 

3. The red corpuscles are the carriers of oxygen from 
the lungs, obtained from the air we breathe, to the various 
tissues of the body. The white corpuscles axe protoplasm 
of a cellular form, not especially functional, — that is, not 
set apart for any particular process that we are yet aware 
of, — yet necessary to the performance of the functions of 
the blood as a whole. 

1 The plasma, or liquor sanguinis, is alkaline, transparent, and composed of water, 
fatty and albuminous matters, salts, and crystallizable substances of organic origin, 
and it forms about three-fifths of the volume of the blood. 

75 



y6 ACADEMIC PHYSIOLOGY. 

The blood is also the carrier of the nutritive elements 
of food to the tissues which it permeates, and it takes 
away, by means of the veins, the waste or refuse material 
from the tissues. 

4. As in the outside world there is a constant inter- 
change of material necessary to the continuance of life — 
the exhalation from the ocean of vapor which, as rain, 
again descends and nourishes the vegetable world ; the 
fall and decay of the leaf, which enriches the soil for the 
reproduction of its kind ; the currents of water, at various 
temperatures, which interchange and regulate the climates 
of the world — so in the microcosm of a human being 
there are interchanges constantly going on ; the reception 
of material from without which is built into the economy, 
being carried to it by the blood, and the rejection and 
throwing off, by means of the various organs of excretion, 
of matter which cannot be incorporated. 

5. The blood, then, cannot be a fluid of unvarying com- 
position. The amount and kind of food, the time of day, 
the degree to which the body has been exercised, — all 
these conditions change the amount and kind of its con- 
stituents. The color of the blood as it courses through 
the arteries is red, but when loaded with the impurities 
of the system, as seen in the veins, it is purple. 

6. Properties of Blood. — Coagulability. — In a short time 
after being drawn from the body, blood becomes viscid, or 
jelly-like ; that is, it has become coagulated. If in a deep 
vessel, it forms a complete mould when removed. If 
blood thus coagulated be allowed to remain in a glass 
vessel for a longer period, it may be seen that a colorless 
fluid exudes from the surface and forms a layer; and later 
on a layer of this colorless fluid will be found on the sides 



THE BLOOD AND ITS CIRCULATION. 77 

and at the bottom of the vessel. This is called the serum} 
and in it the clot floats, shrunken in size. The clot con- 
sists of fibrin, enclosing in its meshes the corpuscles 
of the blood. The fibrin is composed of fine fibres, 
called fibrils. Hence, in coagulating, the blood is 
separated into a fluid portion, the serum, and a semi- 
solid portion, the fibrin, containing the corpuscles. 
Coagulation prevents excessive bleeding from slight 
cuts, etc. 

7. The Red Corpuscles. — The red corpuscles in human 
blood are minute, flat, circular disks, concave on both sides, 
having a diameter of about g^— of an inch and a thick- 
ness of about T2o~oo mcn - 2 ^ placed edge to edge, rather 
more than ten millions of them would be required to cover 
a space one inch square. When one of these corpuscles 
is examined under a powerful microscope, it appears of a 
pale yellowish color ; but when several are seen lying one 
on another, or en masse, the redness becomes obvious, 
and thus these little bodies give to the blood its uniform 
red color. 

8. These corpuscles have a sort of spongy framework, 
and are very soft, flexible, and elastic. They readily 
change their shape in passing through the smallest 
blood-vessels and apertures narrower than their own 
diameters, and resume their proper shape immediately 
afterward. 

9. In composition the red corpuscles are found to con- 
sist of about 56 y 2 parts water, and 43 x / 2 parts solid 

1 Serum is composed of water, 90 parts ; proteid substances, 8 to 9 parts ; fats, 
extractives, etc., 1 to 2 parts. Proteids are albuminoid substances ; the name applied 
to that form most largely existing in the blood is para-globuline. 

2 In different animals the red corpuscles vary in size ; in birds and in reptiles they 
are oval in shape and larger than in man. 



78 



ACADEMIC PHYSIOLOGY. 



matter; 1 and each of them should be considered as a 
minute, spongy, semi-fluid or semi-solid, jelly-like mass, 
rather than as a tiny bag or sac containing fluid. 

10. The White Corpuscles. — These corpuscles are ex- 
tremely irregular and 
ever-changing in form, 
of a yellowish-white 
color, and a little larger 
than the red, being 
2tYj<j of an inch in 
diameter. The white 
corpuscles are not so 
numerous as the red, 
the proportion being 
about as one to five 
hundred. 

11. While the shape 
of red corpuscles is 
changed only by in- 
fluences from without, 
such as pressure, that 
of the white corpuscles 

A, moderately magnified corpuscles. At a and Undergoes Constant 

«are two white corpuscles. The red ones are alteration from changes 
arranged like coins in rolls. B, C, D, E, F, are . . 

highly magnified red corpuscles, in various taking place in their 

positions. I, a red corpuscle distended into a own Sllb^tanCP ThPV 
sphere. G, H, white corpuscles, much magnified. g J 

also exhibit a peculiar 
migratory power (and in this they much resemble a minute 
animal organism found in great numbers in stagnant 

1 The solids are organic matters, in ioo parts of which have been found hemo- 
globin, 90.54 parts. This substance possesses a strong affinity for oxygen, and 
readily absorbs it or unites with it ; but as the tissues have a still stronger affinity for 
oxygen, they absorb it from the red corpuscles, and, in return, replace it with car- 




Fig. 29. Red and white Corpuscles of the 
Blood magnified. 

EXPLANATION. 



THE BLOOD AND ITS CIRCULATION. 79 

water), often getting out of the smallest blood-vessels 
(capillaries) and becoming scattered in the interstices 
of the surrounding tissues, where, in consequence of 
their adhesiveness, they become fixed, undergo changes, 
and become parts of the tissues. White corpuscles in 
the blood of all animals are very nearly equal in average 
size. 

12. Quantity of Blood. — In the human body it may be 
said that from one-tenth to one-thirteenth of its weight is 
that of blood, of which, according to Ranke, one-fourth 
is distributed in the heart, lungs, large arteries, and veins ; 
one-fourth in the liver ; one fourth in the skeletal muscles ; 
and one-fourth in the remaining organs and tissues. 

13. Quality of the Blood. — While the blood is normally 
found to contain all the elements needed for the nourish- 
ment of the entire system, and is being constantly added 
to by constituents derived from food and from the air, yet 
there is probably as much variation in its quality as in its 
quantity in different individuals. " The hygiene of the 
blood requires proper food, exercise, cleanliness of skin, 
right living, and sound organs, and then the system will 
not fail to make use of its natural powers of construc- 
tion, elimination, and repair." Blood may become so 
much impoverished — thin and watery — from neglect of 
hygienic attention, as to render health impossible ; and 
such conditions are often inherited. 

14. The Lymph. — In addition to the blood, and interme- 
diate between it and food, there is another fluid found 



bonic acid. Further, the color of the blood is due to hcemoglobin, which contains a 
considerable proportion of iron oxide. As the blood flows through the capillaries 
surrounding the air-cells in the lungs, the hcemoglobin combines with the oxygen of 
the air, becoming of a bright-red color. 



80 ACADEMIC PHYSIOLOGY. 

widely distributed in the body. This fluid, known as 
lymph, closely resembles the plasma of the blood in 
composition, and is contained in the lyviphatic vessels. 
Lymph represents some of the ingredients of the blood 
and some of the waste matter resulting from the constant 
wear of the tissues. It has been described as " blood 
minus its red corpuscles which becomes changed on enter- 
ing the lungs and mingling with the current." 

15. Lymphatic vessels resemble exceedingly small veins, 
and all parts of the body which have blood capillaries, ex- 
cept perhaps the bone, brain, spinal cord, cartilages, and 
tendons, have also lymphatic vessels mingling with the 
blood vessels. In their course the lymph vessels form in 
some parts of the body, as about the neck, groins, and arm- 
pits, numerous small, solid bodies called lymphatic glands. 
After twining about through the tissues and amidst 
glands, the lymphatics pour their contents into the tho- 
racic duct which empties its liquid into the great vein 
at the left side of the heart, from which it is sent to 
the lungs to be purified before entering the general circula- 
tion. 



CHAPTER X. 

THE CIRCULATION. 



1. The Circulatory Apparatus. — For the purpose of con- 
veying throughout the body the blood, the circulation of 
which is essential to growth, and by which fresh material 
is deposited in place of that which has worn out or become 
unfit for use, there is in the body a circulating apparatus 



THE BLOOD AND ITS CIRCULATION. 



8 



analogous to that by which cities are supplied with 
water. 

2. A powerful and complex machine, the heart, receives 

h 




Fig. 30. The Heart and large Blood Vessels. 



EXPLANATION. 



q y the descending vena cava. 

0, the ascending vena cava. 
■ n, the right ailricle. 

b, the right ventricle, 
k, the pulmonary artery. 

1, I, the right and left branches of this 
artery, going to the lungs on either side of 
the chest. 

m, m, the veins of the lungs, which return 



what the artery sent in, to r, the left auricle. 

a, the left ventricle. 

c, e,f, the aorta, or great artery of the 
body, rising out of the left heart. 

g, the arteria innominata. 

h, the left common carotid artery, going 
up the side of the neck to the head. 

i, the left subclavian artery, going to the 
left arm. 



Note. — The arrows show the course the blood moves in each of the vessels demon- 
strated with the heart : «, the right auricle ; m, m, veins of the lungs ; s, the left coronary 
artery ; p, the veins returning blood from the liver and bowels. 

the blood into its cavities, and, acting as a forcing-pump, 
propels it into an extensive series of tubes, the arteries, 



82 ACADEMIC PHYSIOLOGY. 

by which it is conveyed to all parts of the body to give it 
nourishment. A network of very fine tubes, the capilla- 
ries, variously arranged, connects the arteries with another 
set of large pipes, the veins, and the latter collect all the 
blood, after it has been used, in order to return it to 
the heart, which then pumps it into the lungs, where it 
becomes aerated and gives off impurities. Thus during 
life the blood is in constant motion. " From the heart, 
as a centre, a current is always setting toward the differ- 
ent organs, and from these organs a current is constantly 
returning to the heart." 

3. The Heart. — The heart is roughly estimated to be 
about the size of the fist. . Its weight is from ten to 
twelve ounces in the adult, and it increases slightly in 
size and weight with advancing years. 

4. It is conical or pear-shaped, and is suspended in the 
chest a little to the left of the centre-line, its base upward, 
and its apex or point downward, on a level with the space 
between the fifth and sixth ribs. It is composed of mus- 
cular tissue which contracts regularly at equal intervals of 
time. It is enclosed in a sac of serous membrane called 
the pericardium (Gr. peri, around ; and kardia, the heart). 
In the pericardial sac is a small quantity of fluid — a tea- 
spoonful or two — which lubricates the surface of the 
heart and of the sac, and admits of free movement without 
friction. 

5. Muscular Structure of the Heart. — The muscles of which 
the heart is composed are different from the general 
muscles of the body in several particulars. Their fibres 
are not continuous and separable, but join each other in 
various directions. Again, they seldom have a covering 
or sheath. 



THE BLOOD AND ITS CIRCULATION. 83 

6. There are two layers of muscular fibres, the superfi- 
cial and the deep. The former run spirally around the 
heart, forming a figure 8. These subserve the purpose 
of contracting the heart in such a manner as to cause it 
to empty its contents rhythmically, as will be seen later. 
The deep layers are circular in form. 

7. Cavities of the Heart, Valves, etc. — All animals that 
breathe have hearts divided into four chambers by muscu- 
lar partitions. The right half of the heart is designed to 
propel the blood into the lungs, the left half to propel it 
through the arteries to all parts of the body. Hence, the 
right side of the heart is known as the pulmonary (Lat. 
pulmo, a lung) side, and the left the systemic. Each side 
contains two cavities, an upper and a lower one. The 
upper cavities are known as auricles, the lower ones as 
ventricles. 

8. While the right side and the left side are entirely 
separated by a wall in which there is no opening, the 
auricles and ventricles are not so separated. They are 
so arranged as to allow the blood to pass freely from each 
auricle to each ventricle (but not from the ventricle to 
the auricle) by means of little doors or valves composed 
of strong fibrous tissue prolonged into cords which are 
attached to the walls of the heart. These openings are 
known as the auriculo-ventricular openings. The valve 
between the right auricle and right ventricle is commonly 
known as the tricuspid (i.e., three-pointed) valve, it having 
three leaflets ; that between the left auricle and left ven- 
tricle, the mitral valve, having two leaflets which, when 
open, are supposed to resemble a mitre. 

9. The muscular walls of the left side of the heart are 
thicker and stronger than those of the right side, since 



84 



ACADEMIC PHYSIOLOGY. 



more force is required to drive the blood through the 
arteries than merely to receive it back from the veins and 
propel it to the lungs, as is done by the right side. This 




Fig. 31. Interior of the Right Side of the Human Heart 
EXPLANATION. 
i, superior vena cava ; 2, inferior vena cava ; 3, interior of the right auricle ; 4, semi- 
lunar valves of the Pulmonary artery ; 4', papillary muscle; 5, 5', and 5", cusps of the tri- 
cuspid valve ; 6, pulmonary artery ; 7 , 8, and 9, the aorta and its branches ; 10, left auricle ; 
1 1 , left ventricle. 

is especially true of the left ventricle, whose work it is to 
propel the blood through the whole system. 



THE BLOOD AND ITS CIRCULATION. 



85 



10. Besides the valves already mentioned, there are also 
valves in the aorta (the main trunk of the arterial system), 
and in the pulmonary artery (the artery conveying blood 
to the lungs). 




mu2 



Fig. 32. The Orifices of the Heart seen from above, the Auricles and Great Vessels 
being cut away. 

EXPLANATION. 

P, A, pulmonary artery, and Ao, aorta, with their semihinar valves. R. A. V., right 
auriculo-ventricular orifice, showing the three folds (Iv, 1, 2, 3) of the tricuspid valve. L. 
A. V., left auriculo-ventrictdar orifice, showing its mitral valve of two flaps at m. v., 1 and 
2. A piece of whalebone at b passes into the coronary vein. The tooth-like appearance of 
the left side of L. A. V. is due to the fact that the section of the auricle is carried through 
the auricular appendage seen on the exterior surface of the heart. 

11. In a healthy condition of the heart, all of these 
valves work harmoniously and perfectly ; but in certain 
organic diseases they become deranged, thus leading to 
serious and often fatal results. 

12. Course of the Blood in Circulation. — The minute veins 
in all parts of the body collect the impure blood. These 
veinlets unite and form larger branches which finally cul- 



86 ACADEMIC PHYSIOLOGY. 

minate in two great veins known as the superior vena cava 
and the inferior vena cava, which open into the right 
auricle of the heart. When the auricle is filled, its con- 
traction drives the blood through the tricuspid valve into 
the right ventricle, whence it is forced by contraction of 
that ventricle through the pulmonary artery into the lungs. 
Here the blood is distributed by the branches of the 
artery (numerous hair-like tubes) among the air cells, 
and after its change into arterial blood from contact with 
the air inhaled, it is conveyed by the pulmonary veins 1 to 
the left auricle. By the contraction of the left auricle the 
arterial blood is driven through the mitral valve into the 
left ventricle, by the contraction of which it is propelled 
through the main artery of the heart (the aorta) and its 
branches throughout the whole arterial system, until at 
last it enters the capillaries (the hair-like network of tiny 
blood-vessels connecting the arteries and veins) for the 
nourishment of the tissues. Having performed its mis- 
sion by giving up its nourishing elements, and having 
received in exchange the products of decay and disinte- 
gration, the blood commences at the extremities of the 
venous system its return to the right auricle, whence it 
is again sent to the lungs for purification. 2 Thus we have 
traced the course of the blood on its endless round. 3 

1 To avoid confusion, it is well to state that the only artery that conveys venous 
blood is the pulmonary artery, and the only veins that convey bright or arterial blood 
are the pulmonary veins. 

2 In short, the course of the blood is as follows : From the right side of the heart 
to the lungs ; thence to the left side of the heart ; thence to all parts of the body ; 
thence back to the right side of the heart. It will be noticed that the right side never 
contains anything but dark, venous blood, and the left side always contains bright, 
arterial blood. 

3 In 1602 William Harvey began investigations upon living animals, and in 1616 
discovered the circulation of the blood. Prior to that time portions of the circulatory 
apparatus and their functions had been described by several persons. 



THE BLOOD AND ITS CIRCULATION. 8? 

13. Action of the Heart. — The heart may be viewed as 
a pump, a part of whose action is simply mechanical. 
Continuous in its action, it would not vary a beat in fre- 
quency and force were it not for certain changes in the 
system. Fortunately, it can accommodate itself meas- 
urably to changed conditions in vital processes. In the 
normal state the action is regular, and the quantity of 
blood ejected at each beat is the same. 

14. The alternate contractions and dilations of the auri- 
cles and ventricles are technically termed the systole and 
the diastole. More properly, the diastole is a pause be- 
tween the movements — a period of slight rest. 

15. By opening the chest of an animal and keeping up 
artificial breathing, it has been made possible to see a 
heart in action ; and the following phenomena have been 
observed : First, a filling up of the great veins which 
open into the heart ; then a contraction of these veins 
and a filling up of the auricles, followed by a contraction 
of the auricles and a filling of the ventricles, which is 
called the aurictdar systole. Immediately follows the con- 
traction and shortening of the ventricles, known as the 
ventricular systole. During the contraction of the ventri- 
cles, the aorta and the pulmonary arteries expand with 
the columns of blood thrown into them, and the heart 
rolls or twists to a slight degree from left to right. This 
twisting or rolling movement is due to the " figure of 
8 " arrangement of the muscular fibres previously men- 
tioned. 

16. As the ventricles become empty, they lengthen out 
again ; and this period of relaxation previous to another 
series of movements is called the diastole. At this time, 
also, the heart turns back again, or, rather, untwists. 



88 ACADEMIC PHYSIOLOGY. 

Short as are these periods of relaxation, they afford, in 
the aggregate, much rest to the muscles of the heart. 1 

17. Sounds of the Heart. — When the ear is applied to the 
chest over the heart, two sounds can be heard, viz., a long, 
deep sound, and a short, sudden one, succeeded by a pause, 
which is followed by a repetition of the same sounds. 
The space of time between the first and the second sound 
is so short as to be scarcely measurable, but there is an 
appreciable pause before both sounds are repeated. These 
sounds have been likened to those made in pronouncing 
the syllables liib-diib. It is difficult to determine the 
cause of the first sound, but it is generally agreed now 
that the second sound is due to the closing of the semi- 
lunar valves of the aorta and the pulmonary artery, after 
the blood has passed into them. 

18. Changes in the rhythm, intensity, or pitch of these 
sounds indicate to the physician the character of any dis- 
turbance or diseased condition of the heart. 

19. Cardiac Impulse. — What is called the cardiac or 
heart's impulse is the striking of the lower, pointed end, 
or apex, of the heart against the walls of the chest. This 
occurs at the time of the contraction of the ventricles 
(ventricular systole), and is most easily felt a little to the 
left of the middle line of the chest, between the fifth and 
sixth ribs. 

20. Causes influencing the Heart-Beat. — The average rate 
of the human pulse, which is a measure of the heart-beat, 
is 72 a minute. Children's pulses are more rapid than 
those of adults. During middle life the pulse varies from 
70 to 80, being about 10 more in females than in males. 

1 It has been estimated that each pause is about one-third of a second in duration, 
and that the heart thus obtains more than nine hours of total rest daily. 



THE BLOOD AND ITS CIRCULATION. 89 

21. The heart does not always beat with unvarying pre- 
cision. Besides changes that may have been produced by 
disease, influences which operate upon the nervous system 
affect the heart also. Joy, sorrow, fear, anger, all nervous 
excitement affect the rapidity of the heart's action ; and 
hence, sudden excitements are to be carefully avoided as 
especially dangerous in diseased conditions of the heart. 
The increase in frequency is accompanied by loss of force, 
and vice versa. 

22. " It is true that the heart is made to endure many 
variations, but frequent and rapid changes of heart-beat 
are to be avoided." Later the effects of stimulants will 
be considered, and their effect upon the circulation stated. 
Just here, however, it is desirable to state that " there is 
no effect of alcohol more insidious than the nervous thrill 
it imparts to the action of the heart," and that its frequent 
or continued use is attended with the most disturbing and 
injurious results. 

23. Muscular activity, the position of the body, the 
temperature of the air, the quantity and kind of food, and 
the age and sex of the individual affect the rapidity of 
the action of the heart and vary it in force and character. 
Again, the heart's action varies with the temperament, 
appearing to be slower in proportion as the individual is 
cool and deliberate in his judgments. As examples of 
this, it is said that the pulse of Napoleon Bonaparte aver- 
aged only forty-four per minute, and that of the Duke of 
Wellington about the same. On the other hand, in some 
persons of excitable, nervous temperament the pulsations 
number ninety or more per minute. Very quick action 
tends to exhaust the heart. 

24. The Nerve Force of the Heart. — We have thus far con- 



90 ACADEMIC PHYSIOLOGY. 

sidered the action of the heart and the phenomena of the 
circulation from a mechanical point of view. But this 
beautiful mechanism would be useless without the force 
derived from the nerve centres. 

25. In the first place, in the heart itself there are three 
sets of nerves. The first is that set supplied by the 
masses of nerve cells (called ganglia) in the substance of 
the heart. The second set comes from that part of the 
nervous structure called the sympathetic? which supplies 
force to involuntary muscles — the heart, etc. The third 
consists of branches of a nerve which originates in the 
brain and comes directly to the heart, and is known as 
the pneumo-gastric nerve (Gr. pneuma, breath ; and gaster, 
the stomach). 

The part which each set takes in regulating and direct- 
ing the action of the heart has been studied, and the latest 
researches seem to prove firstly, that the contractions reg- 
ularly " depend upon the ganglia lodged in its substance ;" 
secondly, " that the influence which increases the rapidity 
of its action is exerted through the sympathetic nerves ;" 
thirdly, " It is quite certain that the influence which 
arrests the heart's action is supplied by the pneumo- 
gastric." 2 

26. That the nervous system is the controlling influ- 
ence may be shown, as before stated, by the effect the 
emotions may have upon the circulation and upon the 
action of the heart. Fear blanches the countenance, 
while joy quickens the circulation. Extreme fear or sud- 
den sorrow may arrest the heart's action. It is well to 
remember this in our daily intercourse with friends. 

1 The sympathetic nervous system consists of a double chain of nerve cells or gan- 
glia, running from one extremity of the body to the other, not including the limbs. 

2 Huxley. 



THE BLOOD AND ITS CIRCULATION. 91 

27. It is a senseless and possibly a wicked act to en- 
deavor to startle or frighten a person suddenly, or to 
bring bad news unguardedly. A physical blow can be 
sustained better than one aimed at that most sensitive 
part of the body, the nervous system. When we con- 
sider the intimate relation between the mind and the 
body, and realize that mental shock reacts upon the body, 
sometimes even to death, how careful we should be to 
avoid the danger of such a possible result of a stupid 
trick! 



CHAPTER XI. 

the circulation. (Continued?) 

1. The Arterial System. — The aorta, or main artery, is 
about five-eighths of an inch in diameter, and rises from 
the left ventricle of the heart. It ascends perpendicularly 
about three inches, and then, curving in the form of an 
arch, descends. From the arch it gives off two large 
branches, one to each arm, and two others to supply the 
head, one going up on either side of the neck. Descend- 
ing along the left side of the spine, it sends out branches 
to the ribs ; and when opposite the stomach, a branch is 
sent out to that organ. In like manner, branches convey 
blood to the liver, spleen, and the other intestines. At 
the lower end of the spine the aorta terminates by divid- 
ing into two large branches, one of which goes to each 
thigh. 

2. At the elbows and at the knees each main branch 



9 2 



ACADEMIC PHYSIOLOGY. 



divides into two, and these passing down, one on each 
side of a limb, again subdivide and furnish a small artery 
for each side of each finger, thumb, or toe. 




Fig. 33. 
EXPLANATION. 

a, the trunk of the left common carotid artery. 

f, the occipital artery, going to the muscles of the back of the head. 

b, the larynx, or vocal box. 

n, the external carotid, branching outward. 

k, the temporal artery, felt beating in the temple. 

g, the nasal artery. 

r, the termination of the temporal artery in twigs on the top of the head. 



THE BLOOD AND ITS CIRCULATION. 93 

3. Throughout the body, however, arteries of various 
sizes branch out from the main trunks to supply the dif- 
ferent organs, the muscles, the bones, skin, etc. 

4. Structure of the Arteries. — The arteries are tubes 
whose walls are strong and elastic. The outermost coat 
of these vessels consists of strong connective tissue ; the 
middle coat, of elastic fibres and involuntary muscular 
tissue; and the innermost coat, of a delicate, smooth 
membrane which lessens the friction in the flow of blood 
through the tube. 

5. The heart, although a powerful organ, would not be 
able to force the blood 
through the whole system 
of the arteries, and back to 
itself again by the veins, 
without assistance. The 
maintenance of the circu- 
lation, while mainly due to 
the action of the heart, is 

Ftg. 34. The Semilunar Values of the 
aided by the elastic and Pulmonary Arteries, the Vessel being cut 

muscular middle coat of the and laid open - 
arteries. At each contraction of the heart the blood 
driven into the arteries must push forward the blood 
already contained in them ; and this results in sufficient 
resistance to cause a pressure outward and distension of 
the elastic walls of the arteries. After each throb of the 
heart and removal of its pressure, the muscular coat of 
the arteries contracts and exerts, in turn, a pressure upon 
their contents which not only propels the blood onward, 
but also backward toward the heart ; and if it were not 
for the valves located where the great arteries open into 
the heart, the blood, or a portion of it, would be driven 




94 ACADEMIC PHYSIOLOGY. 

back into that organ. The slightest backward press- 
ure, however, causes these valves to close, and the con- 
traction of the arteries thus serves to keep up the onward 
movement of the blood till the next impulse is given it by 
the heart. 1 

6. The successive dilations and contractions of the 
arteries give rise to what is known as the pulse, which, 
while everywhere present in the arteries, can be felt only 
at points where they run near the surface of the body, as 
in the wrist, in the neck, in the temple, in the ankle, etc. 
The pulse is most frequently felt for in the wrist, simply 
because that is the most convenient place. 

7. When an artery is cut, the red blood emerges from 
it in jets corresponding in numbers and time with the 
beats of the heart ; but the dark outflow from a cut vein 
is slower, and not accompanied by jerks. These differ- 
ences of outflow serve to distinguish between a wounded 
artery and a wounded vein. 

8. Owing to the elastic nature of its walls, an artery 
does not retract and become closed when cut, as a vein 
does ; and hence it is well to know that hemorrhage from 
an artery may be stopped only by pressure applied upon 
it between the heart and the wound. 

9. The Capillaries. — Between the smallest arteries and 
veins, and continuous with each of them, there is a net- 
work of extremely fine blood-vessels, called capillaries 
(Lat. capillus, a hair). Through this network of hair-like 
vessels the blood passes from the arteries to the veins. 

10. The large arteries, as we have seen, divide and sub- 

1 The only arteries which have valves are the aorta and pulmonary artery which 
spring from the heart, and the valves are situated at the points where these arteries 
open into the heart. These valves are pouch-like, similar to those of the veins. 



THE BLOOD AND ITS CIRCULATION. 95 

divide continually. Their branches decrease in size with 
every division, and their walls undergo changes in struc- 
ture. The smaller the artery becomes, the less muscular 
tissue it contains ; and finally, in these smallest blood- 
vessels, the capillaries, we find none of it. Their walls 
are composed of a single thin membrane, and their num- 
ber is beyond computation. They permeate all parts of 
the body except the hair, nails, substance of the teeth, 
the cartilages, and the outer layer of the skin. Indeed, 
so thickly strewn are they in the body that the point of 
the finest needle cannot anywhere be inserted between 
them. In diameter they are only about -3 qW °f an i ncn > 
or just large enough to permit the corpuscles to pass 
through them ; and the interspaces between them are 
occupied by the various tissues. 1 

11. An examination of a frog's foot under a microscope 
shows most beautifully the circulation of the blood through 
the capillaries. A current of blood from the arteries 
courses along, carrying with it the corpuscles. The 
branches finally become so small that the corpuscles can 
only pass in single file, and here the current becomes 
slower and seemingly uncertain ; but the corpuscles pass 
on toward the veinlets and enter the current of the venous 
blood. 

12. In the capillaries the blood undergoes a very re- 
markable and important change. " The circumstance 
that all the tissues are outside the blood-vessels, by no 
means interferes with their being bathed by the fluid 

1 The capillaries are too small to be seen without the aid of a microscope, and 
hence before the discovery of that instrument the anatomists were puzzled to explain 
how the blood passed from the arteries to the veins, as they could detect no direct 
communication. 



g6 academic physiology. 

which is inside the vessels, for the walls of the capillaries 
are so exceedingly thin that their fluid contents readily 
exude through them and permeate the tissues in which 
they lie." * In this way the blood gives up to the various 
tissues the oxygen and nutritious elements which each 
needs, but furthermore absorbs from them, through the 
walls of the capillaries, carbonic acid gas and other waste 
products. Charged with carbonic acid, the blood loses its 
bright color and becomes dark. It is in the capillaries 
then that the arterial blood is reiidered venous, their thin, 
moist walls allowing the change to be effected with per- 
fect ease. 

13. The Veins. — After passing through the capillaries, 
in which the blood gives up its nutriment in exchange for 
waste products, it flows on into the veinlets and then into 
still larger branches or veins. 

14. The walls of the larger veins consist of three coats, 
but the middle coat contains much less muscular and 
elastic tissue than that of the arteries ; and hence the 
veins are flaccid and yielding. When cut across or emp- 
tied, they collapse. 

15. Unlike the arteries, the veins have valves on their 
internal surface which prevent the blood from flowing 
backward. These valves are pouch-like folds of the inner 
wall of the veins, and during the onward flow of the blood 
they offer no impediment to its passage ; but if a vein be 
pressed upon so as to drive backward the blood which it 
contains, the pouch swings out from the wall and opposes 
further backward flow. When a vein is thus pressed 
upon, several little knot-like swellings make their appear- 
ance at different points in its length, and these are the 

1 Huxley. 



THE BLOOD AND ITS CIRCULATION. 



97 



dilations of the walls above a valve which resists the back- 
ward pressure. In the veins of the extremities the valves 
are especially numerous, since the weight of the columns 
of venous blood would tend to interfere with the onward 
circulation but for this provision. Each valve serves to 
check the slightest tendency toward a backward flow, and 
thus the work is distributed. 

16. The veins are more 
numerous than the arteries, 
and can retain nearly twice as 
much blood as the latter. As 
a rule, they lie nearer the sur- 
face of the body than the 
arteries do, and are recogniz- 
able by their blue color. 

17. The current of blood in 
the veins is more rapid than 
that of the capillaries, but slower 
than the arterial current. The 
flow through the veins is con- 
tinued by the pressure of the 
blood in the capillaries, the con- 
traction of muscles through 
which the veins pass, the suction power of the auricles, 
and by the expansion of the chest in breathing, which 
tends to draw the blood into the lungs. 

18. Commencing in the capillaries, as we have learned, 
the veins unite into larger branches, and these into still 
larger ones, all converging toward the heart as do the 
branches of a tree towards its trunk. Finally they all 
become united in two great veins, the vena cava descend- 
ing> formed by the veins of the head and arms, and the 




Fig. 35. Showing the valves of veins. 
EXPLANATION. 

a, part of a vein laid open, with 
two pairs of valves. 

b, longitudinal section of a vein, 
showing the valves closed. 

c, portion of a distended vein, ex- 
hibiting a swelling at a pair of valves. 



98 ACADEMIC PHYSIOLOGY. 

vena cava ascending, formed by those of the legs and 
trunk. These two great trunks connect with the right 
auricle of the heart. 

19. Vaso-Motor Nerves. — Vaso-motor nerves (Lat. vasa, 
vessels) are those which control the movements of the 
muscles lying in the walls of the blood-vessels. From 
the sympathetic nervous system, nerve-fibres are distrib- 
uted to the arteries and capillaries, regulating their con- 
traction, and, consequently, the amount of blood which 
they contain. Under the influence of these nerves the 
arterial coats are kept in a state of permanent constric- 
tion ; but when the nerve-fibres are cut or otherwise lose 
control of an artery, it immediately dilates and allows the 
entrance of more blood, giving rise to a swollen condition 
called congestion. 

20. There is a communication between the vaso-motor 
nerves and the central nervous system by means of which 
the former become subservient to the latter ; and thus 
the supply of blood to each organ is regulated and 
adapted to its necessities. If the nerve stimulus is such 
as to contract the arteries and capillaries of the skin, 
pallor is produced. On the other hand, if the nervous 
control be partially withdrawn, the capillaries dilate, more 
blood enters them, and a ruddy glow or " blush " is the 
result. 

21. Animal Heat. — We have seen that it is necessary for 
the growth and nutrition of the body that the blood shall 
flow to its every part. It is also essential that the tem- 
perature of the blood shall be maintained at a regular 
degree. Now in the destructive changes in the tissues — 
in the combustion in which oxygen is consumed and car- 
bonic acid gas is given off — heat is evolved. Exactly 



THE BLOOD AND ITS CIRCULATION. 99 

where this process takes place is not positively deter- 
mined, but we know that it occurs between the time when 
the nutritive elements are appropriated by the tissues and 
the time when the waste products are given up to the 
venous capillaries to be carried into the veins. 

22. The greatest amount of heat is generated in the 
muscles, as they constitute so large a part of the body 
and are so frequently in motion. The secretory glands — 
the liver, kidneys, etc. — being so full of capillaries, come 
next to the muscles in the amount of heat production. 
Heat does not originate in the blood itself, but is imparted 
to it. 

23. From the slight changes occurring in bone, carti- 
lage, and connective tissue, but little heat is generated in 
them. The digestion of food in the alimentary canal also 
furnishes a small amount of heat. 

24. If there were no means by which the heat thus 
produced could be regulated, the body would soon be con- 
sumed with " living fire." While loss of heat may be 
produced by contact of the body with cold objects, by 
radiation from its surface, etc., its due regulation depends 
mainly upon the perspiratory action of the skin and the 
exhalation of watery vapor by the lungs. The surplus 
heat being thus carried off, the temperature is maintained 
at a regular degree (98^° F.), and this varies none 
through life, excepting in disease. 1 It will be seen in 
another chapter that proper clothing, bathing, exercise, 
and food assist in regulating the bodily temperature. 

1 Aged persons are generally thought to be more susceptible of cold than the young. 
The heat of human beings has, however, been proved to be very nearly the same 
whatever their age or race, whether on a cold winter morning or on the most sultry 
day of summer. 



IOO ACADEMIC PHYSIOLOGY, 



CHAPTER XII. 

HYGIENE OF THE BLOOD AND CIRCULATION. 

1. Quality and Quantity to be Maintained. — " For the life of 
the flesh is in the blood," is an expression often quoted 
from the Scriptures. In order that the blood may indeed 
be the fluid of life, that it may contain the elements ne- 
cessary to the proper nourishment of the body and sup- 
port of its nervous -and muscular vigor, a due amount of 
proper food and pure air must be regularly and contin- 
ually received into the body.- Furthermore, in order that 
the blood may circulate freely and with sufficient rapidity, 
the body must be exercised. 

2. If food be insufficient or of poor quality, the blood 
becomes impoverished ; and if the air inhaled be impure 
or deficient in oxygen, the blood deteriorates accordingly. 
Proper food, pure air, and sufficient exercise are the 
means, in general, by which the quality, quantity, and 
circulation of the blood are to be healthfully maintained. 
In the chapters treating oi food, air, and exercise, the rela- 
tions of these to pure, rich, and freely-circulating blood 
are more fully noticed. 

3. Effects of Pressure on the Veins. — The veins, as we have 
seen, are largely distributed near the surface of the body, 
and are therefore peculiarly subject to the influences of 
pressure, changes in the temperature of the air, etc. 
Having soft, yielding coats, the veins are affected by the 



THE BLOOD AND ITS CIRCULATION. IOI 

slightest pressure ; and if clothing is so tight as to pro- 
duce any noticeable pressure, it will obstruct the flow 
of venous blood toward the heart, and thus retard the 
circulation. If the return of venous blood from any 
part is interrupted, the supply of arterial blood to 
that part is proportionately diminished, and it suffers 
accordingly. Tight garters are a common cause of 
cold feet, and thus make the body generally uncomfort- 
able. Tight sleeves, tightly fitting garments of whatever 
kind, exerting a perceptible pressure, disturb the circu- 
lation. 

4. The great veins {jugulars) which return the blood 
from the head lie very near the surface on each side of 
the neck. Compression of these veins by tight collars 
produces congestion of the blood vessels of the entire 
brain ; and such engorged condition is manifested by a 
sense of pressure or fulness in the head, by dizziness, or 
by headache. Moderate and continued pressure will im- 
pede the circulation in the brain to an extent sufficient to 
weaken the whole nervous system. 

5. Proper Distribution of the Blood. — If the skin is not 
properly cared for and its pores become obstructed, its 
natural action will be interfered with, and less blood will 
enter its minute blood vessels. As a consequence, too 
much blood may be centred in or about internal organs ; 
and hence, to produce a healthful balance, the skin 
should be kept clean and active, and the limbs and 
muscles should be properly exercised. In this way in- 
ternal congestion is relieved by attracting blood to the 
surface. 

6. The Heart and Mental Excitement. — Frequent excite- 
ment tends eventually to cause heart-trouble. While the 



102 ACADEMIC PHYSIOLOGY. 

heart is capable of enduring many variations in its action, 
caused by mental excitement, yet frequent and rapid 
changes of its beat should be avoided. 

7. " Even when greatly obstructed or weakened, the 
heart often succeeds, with the intelligent co-operation of 
the patient, in keeping the blood moving through the 
arteries for many years. Often in disease it has to force 
the blood through a shrivelled opening not much larger 
than a goose-quill, and this it does by working harder, 
thus causing its own enlargement. But the enlarge- 
ment may at length cause a dangerous thinning of some 
portion of its walls. Sometimes the walls of the aorta 
lose their elasticity and swell out into a great, thin 
tumor (aneurism). Sometimes the tough fibres of the 
heart are changed into fat. In such cases a fatal termi- 
nation may long be delayed by avoiding undue excite- 
ment." 

8. Effects of Alcohol on the Blood. — When alcohol 1 is taken 
into the stomach, it does not remain there to be digested, 
but some of it is immediately absorbed into the blood and 
carried into the circulation. -Since the blood is so largely 
composed of water, for which alcohol has a great affinity, 
the action of alcohol upon the blood is very marked. It 
absorbs water from the corpuscles, which, if much exposed 
to its action, shrivel and thus become less capable of 
holding and carrying oxygen and of taking up carbonic 
acid from the blood. Thus it will be seen that the direct 
action of alcohol is to interrupt or prevent that inter- 
change of substances in the capillaries upon which 
the nourishment of the tissues and the elimination 

1 For a description of alcohol and alcoholic beverages, see the chapter upon 
" Drinks (continued). — Narcotics and Stimulants," p. 184. 



THE BLOOD AND ITS CIRCULATION. 103 

of waste particles depend. Again, as the capacity of 
the corpuscles as carriers of oxygen is diminished, oxida- 
tion throughout the body is partially arrested, less car- 
bonic acid is exhaled, and the temperature of the blood is 
reduced. 

9. The habitual presence of alcohol in the blood dete- 
riorates its quality, and thereby tends directly toward 
diseased conditions which manifest themselves particu- 
larly in the heart, liver, kidneys, and lungs, they being 
the centres of the circulation. Deterioration or impover- 
ishment of the blood is probably the first step toward 
starving the tissues which the nutritive fluid should 
feed. 

10. " It appears that the fibrin of the blood is affected 
by the alcohol as follows : If it is exposed to strong alco- 
hol, it is coagulated in the blood-vessels, and thus tends 
to clog the circulation in the capillaries. 1 If it is exposed 
to very dilute alcohol for any considerable length of time, 
as in the case with habitual drinkers, it loses its power of 
coagulation, so that the blood wastes freely from breaks 
or cuts of these vessels. This action of alcohol upon the 
blood is well known to surgeons, who, because of these 
conditions, hesitate to perform such operations upon alco- 
holic patients as may safely be performed upon those 
whose blood is not contaminated by alcohol." 2 

11. Effects of Alcohol on the Heart and Blood-vessels. — Alco- 
hol exerts a paralyzing influence on the vaso-rnotor nerves 

1 So greedy for water is it (alcohol) that it must first be diluted before it can be 
absorbed. If it be not so diluted, it will seize the water from the tissues to which it is 
applied, and will harden and coagulate them. In this way it may even be made to 
coagulate the blood itself, and, in some instances of rapid poisoning by it, death has 
occurred from the coagulation of blood within the vessels or in the heart. — Richardson. 

"■2 " Alcohol : Its effects on Body and mind."— E. F. Broivn, M.D. 



104 ACADEMIC PHYSIOLOGY. 

(those which control the muscular coat of the arteries and 
capillaries). Paralysis of these nerves causes relaxation 
of the muscular coats of the small arteries, and they be- 
come enlarged and swollen with blood in every part of 
the body. This enlargement removes the natural resist- 
ance to an undue rapidity in the flow of blood through 
the vessels which act as a balance-wheel to the action of 
the heart ; and the latter organ, released from this natural 
restraint, is driven at an unusual rate and suffers from the 
"wear and tear." 1 Habitual or frequent stimulation of 
the heart's action by this agent tends to exhaust or weaken 
its muscular power. Consequently, a person after imbib- 
ing alcohol, though he may feel unusual vigor and activity 
from the first effects, will soon suffer from a reaction in 
which the heart will act with less than natural force, the 
brain feel tired, and the muscles feeble. 

12. Alcohol, from constant use, causes changes in the 
muscular structure of the heart, rendering it weaker and 
less able to contract forcibly. Sometimes the effect is 
to soften the muscular heart and to fatten it, a process 
known as fatty degeneration. An unusual effort of a heart 
in this condition may cause its rupture, and terminate in 
sudden death. 

13. In other chapters it will be learned that the habit- 
ual use of alcoholic liquors tends to weaken the power of 
the will, to injure the brain and nervous system, the mus- 
cles, and, in fact, the entire organization. 

14. Effects of Tobacco. — Tobacco tends directly to dis- 
turb the sympathetic nervous system on which the heart 

1 If the number of beats of the heart in twenty-four hours is about 100,000, the 
effect of an ounce of pure alcohol is to increase the number to about 104,000 in the 
same length of time. The cause of this is found partly in the action of the alcohol 
on the blood-vessels and partly in its effect upon the nerves of the heart itself. 



SUGGESTED POINTS FOR QUESTIONS. 105 

depends for healthy action. Irregularity and palpitation 
are often caused by it, and a large percentage of tobacco 
users are more or less troubled with irregularities of 
the heart, the evil effects being intensified if the heart is 
naturally weak. It is an active agent in causing heart 
and artery disease, and its effects are further shown in 
increased fluidity of the blood and resistance to normal 
coagulation. 



Suggested Points for Questions. 

Chapter IX. — 1 . The vital fluid — where. 2. Plasma, corpuscles. 3. Cor- 
puscles — functions, etc.; blood — nutrition, waste. 4. Interchanges neces- 
sary to life — analogy; reception and elimination of material. 5. Varying 
composition of blood — cause, color. 6. Coagulability — mould, clot in 
serum; fibrin — nature; coagulation and bleeding. 7-9. Red corpuscles — 
form, size, number, color, structure, changes in shape. 10, 11. White cor- 
puscles — form, size, number, changes, migration, form tissue. 12. Quan- 
tity of blood, distribution in body. Quality of blood — variation; good blood, 
impoverishment. 14, 15. Lymph, lymphatic vessels, glands; relation to 
thoracic duct and circulation. 

Chap. X. — 1. Circulatory apparatus — purpose. 2. The central organ 
or pump; arteries, capillaries, veins, lungs — functions; constant motion. 
3, 4, 5, 6. Size, shape, weight, location, tissue, and contractility, pericardium 
and fluid, peculiarity of muscles, " figure of 8 " arrangement, circular layers — 
purpose, 7, 8. Cavities; right and left side separated — office ; pulmonary and 
systemic; relation of auricle and ventricle — valves, course of blood. 9. 
Right and left walls compared; left ventricle strong. 10. Valves opening into 
aorta and pulmonary artery. 11. Valves in health and disease. 12. Course 
of circulation. 13. Regularity of heart-action, uniform ejection. 14. Sys- 
tole and diastole. 15. A heart in action — phenomena; twisting motion; 
periods of rest. 17. Sounds of heart — cause. 18. Sounds indicative. 19. 
Cardiac impulse — cause. 20. Rate of beat — pulse in children, adult, 
female. 21, 22. Variation in beat — cause, avoidance ; " alcoholic thrill " — 
effect. 23. Principal influences affecting heart-action; exhaustion. 24, 25. 



106 ACADEMIC PHYSIOLOGY. 

Nerve-force of heart — ganglia, sympathetic nerves, etc., — offices of each. 
26, 27. Nervous system controls heart — emotions and effects; danger of 
shock — possible fatality. 

Chap. XI. — 1. Aorta and branches — head, trunk, intestines, extremities. 
2. Duplex arterial supply of arteries in extremities. 3. Arteries of body in 
general. 4. Structure of arteries. 5. Elasticity of arteries aids heart; 
functions of valves at entrance of great arteries to heart. 6. Pulse — what, 
where. 7, 8. Bleeding from arteries distinguished; cut artery; stopping 
bleeding. 9, 10. Capillaries — location, size, number, structure, function. 
11. Circulation in frog's foot. 12. Blood changed in capillaries — arterial to 
venous, cause. 13-16. Veins — structure, peculiarities, valves, number of 
veins, location, functions, quantity of venous blood, color. 17. Current in 
veins — continued by pressure, suction, etc. 18. Veins unite; vena cavae. 
19,20. Vaso-motor nerves — functions, distribution, result of cutting, rela- 
tion to central nervous system, nerve-stimulus — pallor, blushing. 21-24. 
Animal heat, necessity for maintenance, regularity, local production, amounts 
generated in parts of body; regulation of bodily temperature — degree to be 
maintained; 1. agencies of regulation. 

Chap. XII. — 1. Quantity and quality of blood necessary to health — agen- 
cies. 2. Effects of poor or insufficient food, impure air, etc., on blood. 3, 4. 
Effect of pressure of improper clothing on blood-vessels and circulation — 
neck, extremities. 5. Proper distribution of blood in body — agencies; con- 
gestion relieved. 6. Mental excitement related to heart-trouble. 7. Intel- 
ligent care by patient in heart-disease; fatty degeneration; enlargement*, 
aneurism — avoiding excitement. 8. Effects of alcohol on corpuscles; on 
oxidation and interchange; on bodily temperature. 9, 10. Alcoholic impover- 
ishment of blood — manifest in heart, lungs, etc.; coagulation in blood- 
vessels; undue fluidity; wounds in habitual drinkers — danger of surgical 
operations. 11. Alcohol, the heart, and blood-vessels — paralysis of nerves, 
relaxation, congestion, undue rapidity of blood, "wear and tear," reaction 
and exhaustion following stimulation. 12. Alcohol and structure of heart — 
weakness, fatty degeneration, rupture. 13. Effects of alcohol elsewhere in 
system. 14. Tobacco — effects on nerves of heart; heart disease, unduly 
fluid blood, etc. 



THE RESPIRATORY, OR BREATHING SYSTEM. 



CHAPTER XIII. 

THE RESPIRATORY ORGANS. 

1. Why We Breathe. — Whirled along by the current of 
the circulation, the blood, charged with nutritive matter, 
enters the heart and is thence propelled into all the or- 
gans of the body and supplies to them the nutriment 
which they need ; from them it takes their waste pro- 
ducts, and returns by the veins loaded with injurious or 
useless matter in the form of carbonic acid, water, and 
urea. These refuse matters are separated from the blood 
by the excretory organs ; viz., the lungs, the skin, the kid- 
neys. Each of these organs is especially employed in 
casting out one of the waste products ; thus the lungs are 
concerned principally in eliminating carbonic acid; yet at 
the same time they give off considerable watery vapor. 

2. But the lungs perform a double part. Not only do 
they eliminate waste products, but they effect an inter- 
change of gases between the air which they draw in and 
the blood, — the air giving up to the blood oxygen, without 
which life could not be sustained, and receiving from it 
other gases, etc., unfit to support life. It is necessary 

107 



io8 



ACADEMIC PHYSIOLOGY. 



that we should take into our systems atmospheric air in 
order to obtain oxygen, a substance which, though not 
exactly food or drink, is as important as either. As 
the carbonic acid and water are passing from the blood 
through the lungs into the outer air, oxygen is passing 
from the air through the lungs into the blood and is car- 
ried by it to all parts of the body. 

3. Respiration is therefore a process by which the 
oxygen of the air is introduced into the blood, and by 



EXPLANATION. 

a, the left lung. 
i>, the right lung. 
c, the windpipe. 
d y the heart. 

e, the great artery carry- 
ing blood to the lungs. 

f, the great vein. 

g, the great artery carry- 
ing blood to the body. 



which part of the useless and injurious materials are ex- 
pelled in gaseous form. The drawing in of the air is 
called inspiration; the forcing out of the air, which has 
become changed during its stay in the lungs, is called ex- 
piration—^ two functions are together known as respi- 
ration, or breathing. 

4. The Organs of Respiration. — The respiratory organs are 
those that are essential to breathing. They are located 




RESPIRATION. 



IO9 



in the neck and cavity of the chest, and consist of the 
larynx, tradica, bronchial tubes, and lungs. The passages 
of the nose and mouth may be regarded as the outer 
openings of. the respiratory apparatus ; and the muscles 
of the ribs and the muscular diaphragm, which forms the 
floor of the chest, as furnishing the motive power. 

5. Through the action of these organs atmospheric air 
is carried into the lungs where the oxygen it contains 
passes through a thin mem- 
brane and mixes with the 
impure blood carried to the 
lungs from the right side of 
the heart. As the oxygen 
enters the blood, carbonic J 
acid and watery vapor, which 
are products of the waste or 
decomposition going on in 
the tissues, are cast out and 
expelled from the lungs. 
The following is a brief de- 
scription of the organs of 
breathing and of the func- 
tions of each : — 

6. The larynx. (Gr., a 
whistle), sometimes called 
the voice box, because it 
contains the " cords " or 
membranes by means of 
which the voice is pro- 
duced, is the enlarged, up- 
per part of the air passage 
leading from the base of the tongue to the lungs 




Fig. 37. Back view of the Larynx. 
EXPLANATION. 

i, thyroid ; 2, cricoid ; 3, arytenoid carti- 
lages ; 4, upper ring of the trachea; 5, liga- 
ments; 6, epiglottis. 



It is 



HO • ACADEMIC PHYSIOLOGY. 

composed of cartilages connected by ligaments, and has 
attached to it numerous muscles which are concerned in 
producing sounds. The prominent projection in the 
front and upper part of the neck, commonly known as 
" Adam's apple," is formed by a part of the larynx. 
The opening leading into the larynx from the cavity back 
of the mouth (the pharynx) is called the glottis (Gr., 
glotta, the tongue). It is covered by a lid or valve of 
cartilage, called the epiglottis (Gr., epi> upon ; and glotta, 
the tongue). During breathing, speaking, etc., the glottis 
is open ; but during the act of swallowing it is closed by 
the epiglottis, thus preventing any solid or liquid matter 
from entering the wind pipe. Sometimes, while eating, 
a particle of food enters this opening, and, by irritation, 
causes a severe paroxysm of coughing, and even strangu- 
lation if the intruding mass is sufficiently large. 

7. The trachea (Gr., trac/uts, rough) or wind-pipe is a 
cylindrical tube beginning at the lower part of the larynx, 
and, extending downward about four inches and a half, it 
divides and sends a branch to each lung. It is situated 
just in front of the food tube (oesophagus), and is that 
hard, rough tube which may be felt in the front part of 
the throat. Its walls are composed of soft, fibrous mem-' 
brane, and are strengthened by a series of cartilaginous 
hoops which are incomplete behind, their ends being 
united by muscle and membrane where the trachea comes 
in contact with the food tube. It and its branches are all 
lined internally by a delicate mucous membrane, the sur- 
face of which is formed of a layer of cells covered with 
minute hair-like projections called cilia (Lat. cilium y an 
eyelash). These cilia have a constant fan-like motion 
which tends to drive toward the mouth any foreign mat- 



RESPIRATION. 1 1 1 

ter which may come in contact with the lining of the air 
passages. In this way the lungs are kept comparatively 
free from particles of dust inhaled with the air breathed; 
and when phlegm discharged from the mucous membrane 
during inflammation accumulates in the air passages, it is 
in like manner urged towards the larynx, from which it 
is ejected by coughing. This provision is a protection 
against the constant danger of suffocation arising from 
the accumulation of matter in the air passages. 

8. The bronchi are the two branches of the trachea. 
One of these (the right bronchus) leads into the right 
lung, and the other (the left bronchus) into the left lung. 
The right bronchus is larger than the left, the right lung 
also being larger than the left. These tubes divide and 
subdivide in the substance of the lungs till their tiny 
branches penetrate every part of those organs and termi- 
nate in very minute sacs, called air-cells. As the tubes 
diminish in size, the rings of cartilage which are found 
in all the larger branches become smaller and at last 
disappear, the walls of the smallest tubes being entirely 
muscular or membranous. It will thus be seen that, 
while the trachea and bronchi are kept permanently open 
by their cartilages, the smallest tubes may be almost 
closed by the contraction of their muscular walls. 

9. The lungs, the principal organs of respiration (to- 
gether with the heart and large blood-vessels), occupy 
and nearly fill the cavity of the thorax or chest, and 
consequently their general form coincides with that of 
this cavity. They are two in number, one situated in the 
right and the other in the left side of the chest, being 
separated by a space which is occupied by the heart and 
large blood-vessels. They are spongy, elastic sacks con- 



112 



ACADEMIC PHYSIOLOGY. 



sisting of air-tubes and cells, blood-vessels, and elastic tis- 
sue. In form they are conical, the apex being upward ; 
and they are covered by a membrane, called the pleura} 
which also lines the chest. One layer of this membrane 




Fig. 38. The Lungs in outline, showing relation of larynx, trachea, bronchial tubes, and 
air-cells. 

EXPLANATION. 

i, an outline of the right lung, and 2, of the left lung ; 3, the larynx ; 4, the trachea ; 5, 
the right bronchus ; 6, the left bronchus ; 7, 8, bronchial tubes of the right and left lung ; 9, 
9, air-cells at the terminations of the tubes. 

is so closely attached to the lungs that it can be separated 
only with difficulty ; while the other is reflected back, so 
as to form a sac or bag, and is firmly attached to the 
walls of the chest. 

1 This membrane is often the seat of an inflammation to which the name pleurisy 
is given. 



RESPIRATION. 1 13 

10. The lungs are divided, by deep depressions, into 
lobes, the right into three and the left into two, and these 
are divided again by smaller depressions into lobules. 
Each lobule is a miniature representation of the whole 
lung ; a bronchial twig and a minute artery run into it, 
and veins and other vessels leave it. 

11. The dark venous blood is forced from the right ven- 
tricle of the heart, through the pulmonary arteries, into 
the lungs. These arteries divide and subdivide into very 
small branches which penetrate every portion of the lungs, 
till finally they form fine networks (capillary networks) 
which surround and lie on the walls of the air-cells. The 
extreme thinness of the walls of the air-cells and of the 
minute blood-vessels brings the blood almost in contact 
with the inspired air in the cells. However thin these 
membranes may be, they are capable to confine the air 
and the blood in separate cavities ; but they have also 
the property of allowing themselves to be penetrated by 
certain gases. The oxygen of the air therefore passes 
through them in order to combine with the blood ; while 
those gases contained in this fluid, and which should be 
cast out, separate from it, pass through the walls of the 
cells, and mingle with the air, which carries them out 
with it during expiration. By exchanging carbonic acid 
gas for oxygen gas, the venous blood loses its dark color, 
and becomes converted into bright red arterial blood. 
Thus changed, the blood is conveyed by the pulmonary 
veins (Lat. pulmo, a lung) to the left auricle of the heart 

12. Action of Respiration, or How We Breathe. — The thorax, 
or chest, may be regarded as a completely closed conical 
box having the apex directed upwards ; the back of box 
consisting of the spinal column, the sides formed of the 



114 ACADEMIC PHYSIOLOGY. 

ribs, the front by the breast-bone, the bottom by the 
diaphragm (the broad muscle which separates the chest 
from the abdomen), and the top by the base or root of 
the neck, — the whole completed by the thin walls of 
muscle or flesh which unite them. Thus the chest-cavity 
is itself a closed cavity not in communication with the 
external air, but enclosing the lungs which admit air 
through the windpipe ; the cavity is, however, capable of 
being enlarged by means of muscles which act upon its 
movable walls. 

13. In order that the process of changing venous into 
arterial blood may continue, the air in the cells of the 
lungs must be frequently renewed. To accomplish this, 
the external layer of muscles between the ribs (the inter- 
costal muscles, Lat. costa, a rib) contract and raise the 
ribs and breast-bone, thus making the chest-cavity wider 
from side to side, and from front to back ; at the same 
time the diaphragm contracts- and sinks down, pushing 
the abdominal organs downward, thus increasing the depth 
of the chest from the neck downwards. In this way the 
chest-cavity is made larger in all directions by the con- 
traction of these muscles ; and the tendency is to pro- 
duce a vacuum. As the external air cannot go directly 
into the chest-cavity itself, it presses through the air- 
passages of the nose or mouth and thence through the 
windpipe into the lungs, distends the little elastic air-cells, 
and expands the lungs, so that they fill the enlarged space 
in the chest. Thus a certain amount of fresh air is added 
to that already contained in the lungs, and this process is 
called inspiration. As soon as this has occurred, the 
muscles in question relax, the diaphragm ascends, and 
other muscles lower the ribs and breast-bone and thus 



RESPIRATION. I I 5 

diminish the cavity ; the lungs and air-cells collapse under 
the pressure of the walls of the chest, and by their own 
elasticity, and a portion of the air contained in them is 
forced out through the air-passages into the outer air. 
This latter process is called expiration. 

14. " It thus appears that the thorax, the lungs, and the 
trachea constitute a sort of bellows without a valve, in 
which the thorax and the lungs represent the body of the 
bellows, while the trachea is the pipe ; and the effect of 
the respiratory movements is just the same as the approx- 
imation and the separation of the handles of the bellows 
which drive out and draw in the air through the pipe. 
There is, however, one difference between the bellows 
and the respiratory apparatus, of great importance in the 
theory of respiration, though frequently overlooked ; and 
that is, that the sides of the bellows can be brought close 
together so as to force out all, or nearly all, the air which 
they contain ; while the walls of the chest, when approx- 
imated as much as possible, still enclose a very considera- 
ble cavity ; so that, even after the most violent expiratory 
effort, a very large quantity of air is still left in the 
lungs." And this brings us to a consideration of the 
capacity of the lungs and of — 

15. Tidal Air, Supplemental Air, Residual Air, and Comple- 
mental Air. — The air which passes in and out of the lungs 
in ordinary, quiet breathing is conveniently called tidal 
air, and amounts to from twenty to thirty cubic inches in 
the adult person. 

16. About 200 cubic inches of stationary air remain in 
the lungs after each ordinary expiration ; but by making 
a very deep expiration about ioo cubic inches of this can 
be expelled, and this is called supplemental air. 



IIO ACADEMIC PHYSIOLOGY. 

17. The amount of air which remains and cannot be ex- 
pelled is about ioo cubic inches, and is termed residual air. 

18. From the foregoing statements it follows that, after 
an ordinary inspiration, the lungs contain 230 cubic inches 
of air. By making the deepest possible inspiratory effort, 
another 100 cubic inches may be added, and this is signifi- 
cantly called complcmental air. 

19. It further follows that the fresh, inspired air cannot 
directly reach the air-cells at all. The supplemental and 
the residual air, taken together, are, under ordinary cir- 
cumstances, stationary ; the tidal air alone being that 
which leaves the lungs and is renewed in ordinary breath- 
ing. Hence it becomes evident that the exchange of car- 
bonic acid for oxygen is chiefly transacted by the station- 
ary air, which assumes the part of an agent between the 
blood and the fresh, tidal air; but as there is nothing in- 
terposed between the fresh tidal air and the stationary air 
in the lungs, and as both are aeriform fluids in contact and 
continuous, they must effect the exchange between them 
according to the ordinary laws which govern the diffusion 
or intermingling of gases, though the exact mode in 
which the change is effected is not fully understood. 

20. Difference between Inspired and Expired Air. — The ex- 
tent to which changes take place in the body may be un- 
derstood by comparing expired with inspired air. The 
expired air differs from the air inspired in the following 
particulars : — 

(a) Ordinarily, inspired air contains 21 parts of oxygen, 
about 79 parts of nitrogen, and not less than .04 parts of 
carbonic acid ; while expired air contains about 5 parts 
more carbonic acid gas and 5 parts less oxygen, the quan- 
tity of nitrogen remaining about the same. 



RESPIRATION. 117 

(£) Whatever the temperature of the external air, that 
of the expired air is nearly as warm as the blood, or be- 
tween 98 and ioo°. 

(V) No matter how dry the external air may be, that 
expired contains a large amount of watery vapor, being 
nearly or quite saturated. 

21. Rapidity and Amount of Respiration. — An adult at rest 
breathes about fifteen times a minute. Children breathe 
much more rapidly than adults ; and the circulation of the 
blood in children is correspondingly more rapid. 

22. From statements already made, it will be easy to 
calculate the quantity of air inspired and expired in a 
given time. In twenty-four hours this would amount to 
between three hundred and seventy-five (375) and four 
hundred (400) cubic feet of air passed through the lungs 
of an adult man, taking little or no exercise. In other 
words, this amounts to about eighteen cubic feet of oxy- 
gen taken in, and an equal quantity of carbonic acid gas 
given out, in the time mentioned. Shut up in a close 
room having the form of a cube whose sides are seven 
feet, a man will have passed through his lungs every par- 
ticle of air of that room, and one-fourth of the oxygen it 
contained will be replaced by carbonic acid gas. 1 In such 
an instance, when one or two per cent of the oxygen had 
been consumed, a feeling of general uneasiness accom- 
panied by giddiness or headache would arise. As the 
loss of oxygen increased, there would not be sufficient of 
it in the inspired air to change the color of the blood ; 

1 The quantity of water given off in the breath from the lungs in twenty-four 
hours varies greatly, but the average amount may be placed at about a half-pint, 
equal to about nine ounces. It may fall below this amount, or increase to two or 
three times the quantity. 



Il8 ACADEMIC PHYSIOLOGY. 

and this would certainly be the fact when the loss of oxy- 
gen and the gain of carbonic acid gas rose to ten per 
cent. In consequence, the blood would be venous through- 
out the system ; carbonic acid gas, which is slightly poison- 
ous, would accumulate in the blood, and this together with 
the oxygen starvation (more particularly the latter 1 ) would 
quickly cause death from asphyxia (Gr. <?, without; and 
spkuzio, I throb), a stoppage of the circulation of pulse, 
caused by suffocation. In choking, strangling, or drown- 
ing, asphyxia ensues from the fact that oxygen cannot 
enter the blood, while the latter soon becomes saturated 
by the rapidly accumulating carbonic acid gas. 2 

23. From the foregoing, necessity for providing means 
for the removal from rooms of the expired air, and for the 
access of pure air, will be understood. 

24. Diaphragmatic and Costal Breathing. — In tranquil 
breathing, the inspiration of air is effected principally by 
the diapJiragm in men, while in forced inspiration, or after 
rapid exercise, the intercostal muscles are brought into 
play in moving the ribs. In women, on the contrary, the 
diaphragm does not perform so important a part as the 
ribs. Thus it appears that we may have either dia- 
phragmatic respiration or costal respiration. As a rule, 
however, the two forms of breathing coincide and aid 
one another. 

1 In such case death would probably be caused by the deprivation of oxygen rather 
than by the poisonous effects of carbonic acid gas, it having been proved by experi- 
ment that air containing ten or fifteen per cent of this gas produces no immediate 
effect on the system if the supply of oxygen be proportionately increased. 

2 Conversely, the breathing of an atmosphere too highly oxygenized produces 
changes in the respiratory process, causing it to cease in time ; the blood becomes too 
much arterialized ; and the balance being destroyed, the apparatus ceases to act. Va- 
rious drugs or medicines produce similar derangements. Ammonia stimulates the 
centres. Belladonna first stimulates then paralyzes. Opium, ether, chloral, and many 
other drugs also have a paralyzing effect. 



RESPIRATION. I 19 

25. Persons who breathe chiefly by means of the upper 
ribs are easily fatigued and very soon " out of breath." 
This is apparent in women when the corset compresses 
the base of the chest and interferes with and impedes the 
action of the diaphragm and lower ribs ; under such con- 
ditions the efforts of the inspiratory muscles become 
painful, fatigue is rapidly induced, and the inspiration 
becomes more frequent because it is always incomplete 
and insufficient. 

26. " Deep breathing, using the diaphragm and the 
abdominal muscles, of which the majority of women have 
no knowledge, gives the most efficient exercise to the 
digestive tract. The 'A, B, C ' of health lessons is in 
deep, natural respiration. The lungs must be filled to 
the bottom. The most eminent vocal instructor in this 
country asserts that 'the main action should be at the 
waist and below the waist.' Animals and children have 
this natural breathing. Men and women lose it from 
lack of exercise and constriction of dress." Health, 
strength, power of endurance, and length of life depend 
very greatly upon lung capacity. 

27. Diaphragmatic breathing is practised by mountain- 
climbers, gymnasts, and skilful singers, the habit being 
induced either by instinct or by a well-directed education. 

28. Respiratory Sounds or Murmurs. — As elsewhere re- 
marked, there are certain secondary phenomena which 
accompany and are accounted for by the action of the 
heart ; so also there are similar phenomena which accom- 
pany the action of the respiratory apparatus. These are 
the respiratory sounds, and are audible when the ear is 
applied to any part of the chest which covers the lungs. 
They resemble the sounds produced by breathing through 



120 ACADEMIC PHYSIOLOGY. 

the mouth when the lips are very nearly closed, and are 
louder at the upper part of the chest, over the bronchi, 
than elsewhere. It appears that these sounds are pro- 
duced by the air in its movements through the air-pas- 
sages. 

29. When a person is in a normal condition and awake, 
breathing takes place without exterior sound if the move- 
ment is moderate. If, however, respiration is strong and 
deep, a sound is caused by the movement of the air 
through the passages of the nose, or through the mouth. 
Snoring is caused during sleep when the entering column 
of air breaks upon the soft palate. 

30. On applying the ear to the chest of a person in 
good health, a soft, regular murmur is heard in rhythm 
with the breathing. Several diseased conditions cause 
changes in the nature of this murmur, suppress it, or 
produce other sounds which act as signs to the physician, 
enabling him to determine the condition of the organs of 
respiration. 

31. Respiration influenced by Atmospheric Pressure. — The 
density of the air diminishes with the atmospheric pres- 
sure; that is, the air is less dense in elevated regions 
than in lower ones, on the seacoast for example. A 
given quantity of dense air contains more oxygen than an 
equal quantity of rarefied air. Hence it is that in order 
to supply the lungs with the quantity of oxygen essential to 
arterialize the blood, it is necessary to respire more rap- 
idly upon high mountains than when breathing the air of 
plains or valleys. It is, however, only when the height is 
considerable and the ascent is rapidly made that this in- 
creased rapidity of breathing is perceptible. 1 

* In balloon ascensions made to the height of more than 20,000 feet (that of Guy 



RESPIRATION. 121 

32. The exertion of walking in climbing mountains 
increases the disturbance caused by the rarity of the air ; 
but, when in a single day an altitude of sixty-five hundred 
feet is reached, a very perceptible hastening of respiration 
and the pulse is experienced, in many instances accom- 
panied by peculiar disturbances which have been called 
mountain sick?iess, the most remarkable symptoms of 
which are fatigue or partial paralysis of the muscular 
system, especially of the muscles of the legs. The higher 
the ascent the shorter the distance that can be passed 
without resting. Inclination to sleep, weakened action 
of the heart, and loss of animal spirit sometimes accom- 
pany the general exhaustion. In some cases mountain 
sickness closely resembles sea-sickness. 

33. The adaptability of the human organism is such, 
however, that man has easily acclimated himself to the 
rarefied air of immense heights, and suffers no incon- 
venience from it ; 1 and it may be added that the difficul- 
ties of respiration are not equally experienced by all who 
enter a rarefied atmosphere. Some persons are but little 
disturbed, and soon become accustomed to the change, 
while others suffer for a long period of time. This brings 
us to the consideration of air in general, of its effects 
when it is impure, and of the necessity for its renewal 
when contaminated in order to maintain healthy existence. 

Lussac, for instance), requiring only a few hours, respiration is disturbed and greatly 
hastened ; and as no physical exertion was required, this condition could only be 
attributed to the diminished atmospheric pressure. 

1 In Peru land is cultivated at an altitude of 13,450 feet above the level of the sea. 
La Paz is located in the Andes at a height of 12,195 feet, while in Thibet there are 
villages at an elevation of 16,400 feet. 



122 ACADEMIC PHYSIOLOGY. 

CHAPTER XIV. 

THE AIR WE BREATHE. 

1. The Atmosphere. — The earth is surrounded by an 
envelope of air commonly called the atmosphere. Esti- 
mates or opinions vary greatly in regard to the thickness 
of this covering of air ; but as regards the necessity of 
pure air as a condition essential to healthy existence, all 
will agree. It has been remarked elsewhere that, without 
food, life may still be prolonged for days ; without air, on 
the contrary, life becomes extinct almost instantly. When 
air is impure its effects may be traced throughout the 
entire system ; and many diseases are due either to its 
impurity as a whole, or to the germs of disease which 
impure air is known to contain and distribute. 

2. Pure air consists of a mixture (iwt a chemical combi- 
nation) of two gases, oxygen and nitrogen, together with 
varying proportions of carbonic acid, watery vapor, and 
other matters. While the oxygen and nitrogen are essen- 
tial constituents of the atmosphere, the other matters 
although rarely, probably never, entirely absent from air 
even when it is pure, may be regarded as accidental com- 
ponents which are liable to be so increased, under cer- 
tain circumstances, as to be highly injurious to animal 
life. 

It has already been roughly stated that air is composed 
of twenty-one parts of oxygen and seventy-nine parts of 
nitrogen. A more exact statement of air composition may 
be made as follows : — 



RESPIRATION. 123 

In one hundred parts of pure air there are — 



Oxygen 20.99 parts. 

Nitrogen 78.97 " 

Carbonic acid 04 " 

Watery vapor } 

Ozone / traces. 

Ammonia ) 



3. Oxygen, the most active of the gases essential to the 
composition of air, has been mentioned frequently, and 
its offices in respiration have been stated in the preceding 
chapter. It is an invisible gas which powerfully supports 
combustion or burning, but is not itself combustible. 
Oxygen forms about one-fifth of the volume of the atmos- 
phere, and is that element of the air which supports 
combustion and animal life. It also forms eight-ninths of 
the weight of water, and is so abundant in the earth's 
crust that it is estimated to form more than one-third of 
the weight of the globe. Oxygen is, in fact, the vital 
principle of the atmosphere ; and without it, combustion 
and life would both be impossible. 

4. Nitrogen is a very inactive gas, so far as animal life is 
concerned. Its office in the atmosphere is to dilute the 
oxygen and modify its action, being mixed with the latter 
gas in proportions which render the air breathable and fit 
to sustain animal life. Nitrogen appears to pass in and 
out of the lungs unchanged ; and little, if any, of this gas 
is absorbed into the blood. 

5. The Accidental Components of Air. — The chief of the 
gases spoken of as accidental, or not essential to the air, 
is carbonic acid gas. Whenever the apparently trifling 
quantity present in pure air is slightly increased, impurity 
of the air results. It is this gas, as we have learned, 



124 ACADEMIC PHYSIOLOGY. 

which is given off from the lungs as a waste product. 
The substances commonly used for lighting and warming 
rooms contain carbon and hydrogen as their chief constit- 
uents ; and when they are burned, carbonic acid gas and 
watery vapor are given off and increase the quantity of 
these in the air. When the burning is not complete, 
particles of carbon 1 (soot) escape unburned into the 
air. 2 

6. It may be of interest to note that, since animals are 
continually consuming oxygen from the air by respiration, 
it must be replaced, and that this is done by plants. 
Green plants in the daytime or in the presence of light, 
absorb carbonic acid from the air and decompose it into 
oxygen and carbon, retain the carbon for food, and give 
off the oxygen into the air. Flowers of plants and ripen- 
ing fruits, however, absorb oxygen, and give out car- 
bonic acid. Plants which, like the fungi, are not green, 
habitually absorb oxygen and send out carbonic acid. 3 
It will thus be seen that carbonic acid gas in excess of 
the normal amount constitutes one of the chief causes 
of impurity of atmosphere in and about the habitations of 
men. 

7. The watery vapor contained in the atmosphere varies 



1 Carbon is a solid element which exists in a variety of forms. As a natural 
mineral substance we are familiar with it as graphite (plumbago or black-lead), hard- 
coal, and the diamond, the latter being its purest crystalline form. Charcoal, lamp- 
black, and soot are artificial forms of carbon. 

2 Partially burned fats under some circumstances give off an acrid and very 
poisonous compound called carbonic oxide ; and thus when these substances are not 
perfectly burned the air is rendered much more impure than when they are thoroughly 
burned and produce carbonic acid and watery vapor. 

3 Green plants, however, even in the light, absorb small quantities of oxygen, and 
give off a small amount of carbonic acid gas, these processes constituting respiration 
whether in plants or in animals. 



RESPIRATION. 125 

greatly in quantity, the higher the temperature of the 
air the more water it can contain, and vice versa. It 
is only very rarely that the atmosphere is saturated 
with watery vapor, there being present usually only 
from one-half to three-fourths of the quantity re- 
quired for complete saturation. Air expired from the 
lungs, on the contrary, is saturated with watery vapor 
which represents so much waste material. It has 
been estimated that from nine to ten ounces of water 
are given off by the lungs of an adult in twenty-four 
hours. 

8. Ammonia exists only in the slightest traces in pure 
air. In air expired from the lungs the quantity of ammo- 
nia is very small, while the organic matter given out has 
been estimated at about three grains in twenty-four 
hours. 

9. Ozone (Gr. smell or odor), so called because it has a 
peculiar odor, is an altered and condensed form of oxygen. 
It is a powerful disinfectant and deodorizer, and it rapidly 
consumes and destroys foul organic matters with which it 
comes in contact. This gas is contained in sea-air and in 
mountain-air, and is present in air during thunder-storms 
and during a fall of snow. It is never found in tainted 
air, and its presence is regarded as a proof of the purity 
of air. 

10. Dust. — In addition to the deleterious gases which 
the air is liable to contain, especially wherever human 
beings are crowded together, certain solid particles are 
suspended in the air as dust. These minute particles are 
readily seen dancing as "motes" in the track of a sun- 
beam. They consist very largely of mineral matters de- 
rived from the soil. Included among these particles are 



126 ACADEMIC PHYSIOLOGY. 

found dead organic matter, 1 as the scales of the scarf-skin ; 
the fibres of clothing, or of cotton and wool ; vegetable 
dusts of various kinds, as the pollen of plants, the spores 
of fungi, etc. The air in and near large towns contains 
soot produced in the burning of substances (especially of 
coal) used in warming and in manufacturing. In many 
manufacturing operations dust is produced and becomes 
diffused in the air. The breathing of air containing 
much dust of any kind causes irritation of the respiratory 
organs ; and from the fact that small particles get into the 
lungs and set up irritation there, lung diseases of various 
kinds, including consumption, are prevalent amongst those 
who are exposed to such air. 

11. Breathing should, as a rule, be conducted through 
the passages of the nose ; the mouth should be employed 
in breathing only when the nasal passages are so ob- 
structed as to render them inadequate for the purpose, or 
when for other reasons mouth-breathing becomes abso- 
lutely necessary. Air breathed through the nose travels 
farther over warm surfaces of the air-passages, and hence 
its temperature is more agreeable to the lungs than when 
inhaled by the mouth. Particles of dust are, moreover, 
more fully arrested and less liable to get into the lungs 
when breathing takes place through the nose. It is best, 
therefore, to regard the nasal passages as being designed 
for the ordinary purposes of respiration, and the mouth as 
intended to be so employed only in cases of necessity. 

12. The use of a very simple " respirator " containing a 
small quantity of cotton-wool, through which the inspired 

1 Organic substances (animal and vegetable substances) are subject to decay, a 
chemical change by which they are decomposed into gases which pass off into the 
air, Organic matters here meant are the worn-out particles of the body. 



RESPIRATION. 127 

air might be filtered and the dust prevented from entering 
the air-passages and lungs, would undoubtedly very much 
decrease the death-rate from bronchitis and consumption 
among those who work in dust-laden atmospheres. 

13. Bacilli. — The air also carries and distributes many 
of the lower forms of life, among which are the "germs" 
of various diseases. When breathed or otherwise received 
into the human system, these germs or bacilli produce, 
under certain favorable conditions, the diseases from which 
they originate. For instance, it has been proved that 
consumption develops a special germ or bacillus in the 
tissues of the lungs, and that these bacilli, which are 
microscopic in size, are exhaled from the lungs of con- 
sumptive patients in breathing. Their presence in the 
air of the wards of hospitals for consumptives has been 
demonstrated by experiment. And thus it is in regard to 
the bacilli of yellow fever, typhoid fever, cholera, etc., 
the presence of actual disease-particles in the air being 
no longer a matter of mere theory, but one of absolute 
certainty and proof. Disinfection of the air, or the pro- 
cess by which certain fluids are diffused so as to fill the 
atmosphere with their active principles, is simply a work 
of destroying the germs, or lower forms of life, which air 
is known to contain. There is little doubt that epidemic 
diseases are spread by a diffusion of their bacilli in the 
air which carries them. 

14. Many bitter experiences of disease and death result- 
ing from tainted air should prove more than sufficient to 
impress the truth that fresh air, like pure water, is 
imperatively necessary for health. 



128 ACADEMIC PHYSIOLOGY. 



CHAPTER XV. 

VENTILATION AND THE REMOVAL OF WASTE MATTERS. 

1. Object of Ventilation. — A constant supply of fresh air 
is in the highest degree essential to health. Without it, 
as we have seen, the lungs cannot supply to the blood the 
oxygen necessary for its purification, and all the tissues of 
the body suffer in consequence. In short, pure atmos- 
pheric air is an absolute necessity for perfect nutrition, 
and all available means of obtaining it should be adopted 
in every house, private and public. 

2. In densely inhabited cities, and in occupied rooms, 
the atmosphere is never found in its natural purity. 
Smoke, dust, and gases from factories of various kinds, 
tend to contaminate the air. The germs from decompos- 
ing animal and vegetable substances when not removed 
also add largely to its impurity and become causes of 
disease. 

3. In rooms into which the outer air does not have free 
ingress, the oxygen is soon more or less exhausted even 
by one or two persons. Lights and fires when employed 
in such rooms exhaust the oxygen still more rapidly. The 
air becomes loaded with exhalations from the skin, and 
over-charged with carbonic acid gas given off by the lungs. 
Unless fresh air is admitted, the vitiated air must be 
breathed again ; and it then not only fails to supply the 
oxygen required, but it poisons the body by carrying back 
impurities into the blood. 



RESPIRATION. 1 29 

4. The object of ventilation is a twofold one. It is 
desirable to provide for the removal of the foul air, and to 
secure a sufficient supply of pure air, effecting the inter- 
change in such a manner that there shall be no draughts 
or the exposure of the occupants of the room to cold or 
undue temperature. 

5. When scientifically applied, ventilation involves cal- 
culations regarding the amounts of air needed and the 
frequency of its renewal in order to insure its purity, and 
considerations relative to the best means of securing its 
entrance and exit. Ventilation is a complex subject, and 
the difficulty of applying or adapting effective methods to 
the existing architecture of our houses no doubt accounts 
for the fact that it has been so extensively neglected. 

6. Ventilation Ignored in the Construction of Dwellings. — " As 
our houses are ordinarily built, the question of ventilation 
is practically ignored by architects. For light, for water- 
supply, and for warming, provision is made ; but to the 
renewal of air no consideration is given. Each room is 
practically an air-tight box, depending for ventilation, 
when the windows are closed, on mere chance — on the 
fireplace and chimney, on the crevices of the doors and 
windows, and on the space which may exist between the 
door and the flooring. In the higher era of sanitation to 
which we are advancing, the ventilation of a house will 
form as important a consideration in the minds and prac- 
tice of architects as the size of the rooms and the cost of 
materials. In ancient times, ventilation formed a topic 
which received considerable attention. The Chinese have 
long made the subject a study ; and in classic times, the 
Greeks and Romans used fans and fires as means of ven- 
tilating their domiciles. Even in the bee-hive, ventilation 



I30 ACADEMIC PHYSIOLOGY. 

is practically carried out by the flapping of the insects' 
wings ; and the modification of nature's ways and means 
to the wants of animal life is thus illustrated in a thor- 
oughly practical fashion." 

7. Principles and Means of Ventilation. — In the ventilation 
of rooms and apartments the currents of the atmosphere 
may be utilized ; fires may be so employed as to increase 
the strength of air-currents ; or mechanical means, such 
as fans, pumps, propellers, etc., may be employed to set 
the air in motion. It is not practicable, and is not our 
purpose, to describe here the more technical kinds of ven- 
tilating apparatus ; but it is important that consider- 
ation be given to the means which may be employed 
conveniently in ordinary houses and under ordinary con- 
ditions. 

8. The mechanical or artificial means of ventilating by 
fans, or other apparatus, are highly useful and, in fact, 
indispensable in manufactories and other large buildings 
in which it becomes necessary to provide for the rapid 
removal of dust and other impurities. 

9. For successful ventilation the air taken must be pure 
(not received from other apartments or contaminated 
sources), and must pass continually into the room, suffi- 
cient provision being made for the exit of the impure air. 
The entering air must not be so directed as to cause a 
draught, but should be distributed equally, as far as pos- 
sible, to all parts of the room. 

10. We now proceed to consider what is called natural 
ve?itilation, in which the process is carried on by means of 
the wind and by means of variations in the weight of the 
air due to differences in its temperatiwe, without apparatus 
to produce currents. 



RESPIRATION. I3I 

11. Natural Agents of Ventilation. — First, the wind is a 
powerful agent of ventilation. Even a gentle breeze, one 
moving not more than a mile an hour, will change the air 
of a building thoroughly if the windows are open on both 
sides of it, and are in the line of direction, or nearly so, 
in which the breeze is moving. But the irregularity of 
the wind makes it unreliable as a ventilating agent ; 
although seldom perfectly motionless, at times it moves 
too rapidly to be employed satisfactorily, especially in 
cold weather. In warm weather, contrivances are not 
required ordinarily to secure ventilation. The windows 
and doors being opened, the air of the house is changed 
rapidly unless the outer air happens to be quite motionless. 

12. Probably the most important and reliable agent that 
can be utilized in natural ventilation is found in the move- 
ments produced in the air by variations in its weight 
caused by differences in its temperature. Assuming that 
the air outside is cold, as in winter, and that the air of 
rooms is warmed by radiation from the bodies of human 
beings and sometimes by fires, the cold air outside, being 
heavier and exerting a greater pressure than the warm air 
inside the room, will force its way in through any opening 
that is provided. Bearing this principle in mind, we pro- 
ceed to consider some of the simple methods of ventilat- 
ing rooms and dwellings. 

13. Methods of Ventilation. — The principal points to be 
considered are, firstly, the positions of the air-inlets and 
air-outlets. Fresh air should not be allowed to enter 
near the level of floor, as draughts would be thus caused, 
and dust and other injurious matter would be liable to be 
carried from the floor into the air of the room. Secondly, 
the openings for the entrance of air should be above the 



132 ACADEMIC PHYSIOLOGY. 

level of the heads of occupants of the rooms ; and it is impor- 
tant that the in-flowing air should be directed upwards to 
the ceiling and caused to descend gradually, diffusing 
itself through the air of the room and making its compo- 
sition uniform. For if an opening is made directly 
through the wall of a room above the heads of the occu- 
pants, as in lowering the upper sash, the cold air will pour 
in and fall down in a stream at a short distance from the 
opening, and therefore the necessity for giving it an up- 
ward direction. It should take the form of a fountain, 
not that of a cascade. The entering current may be sub- 
divided by means of numerous small apertures or perfora- 
tions, or by conical openings (the large end of the opening 
being next the room) which tend to disperse the entering 
air. 

14. A simple method of ventilation by means of win- 
dows is as follows : If an ordinary sash window is opened 
at the bottom, the air enters too low, and is not directed 
upward ; while if it is opened at the top, entering air pours 
down upon the heads of those in the room. However, by 
raising the bottom sash and inserting beneath it a strip of 
board which shall extend from side to side, the top of the 
lower sash is raised above the bottom of the upper sash to 
an extent equal to the depth of the board. In this way 
the two sashes are separated, and the air entering between 
them is directed upward by the top part of the lower sash. 
This simple plan is of value in ventilating rooms to which 
other methods cannot be applied, and is especially valu- 
able in sleeping-rooms. 1 

1 " According to the laws which regulate the expansion of gases, air expands when 
heated, and contracts on cooling. Warm air, being lighter than cold air, ascends. As 
it passes upwards, it becomes cooled through contact with the walls, glass, etc., of the 



RESPIRATION. 1 33 

Another simple expedient consists in cutting away a 
portion of the lower cross-piece of the upper sash, so that 
when the window is closed the air rises vertically into the 
room close to the window-panes of the upper sash. By 
placing in the openings narrow boxes (without top or bot- 
tom) filled with cotton-wool, the entering air may be fil- 
tered and soot and dust separated from it. Very fine 
gauze netting may be substituted for cotton-wool. 

15. Windows swung on a pivot midway of their length, 
the upper half sloping inwards and the lower outwards, are 
very effective ventilators for closets and small rooms. For 
large rooms in which great numbers of people congregate, 
such as assembly rooms, churches, etc., and where im- 
mense quantities of fresh air should be supplied, the most 
suitable windows are composed of several sashes which 
slope forward into the room when they are opened, and 
give the entering air an upward direction. 

16. A room may also be ventilated by making an open- 
ing through the wall to the outer air, high up, but not too 
near the ceiling. A board (provided with cheek-pieces at 
its ends) fastened against the wall below the opening and 
sloping inward and upward, will give the required upward 
direction to the air which enters. If the opening is located 
too near the ceiling, the entering air strikes the ceiling 

room, and in consequence descends. Thus the colder air in a room will tend to force 
upwards the warm air, and the rapidity with which this interchange may take place 
will depend on the size and other conditions connected with the openings through 
which the air has to pass. It becomes clear, therefore, that wherever there exist 
openings through which the warm air in a room may be placed in communication with 
the colder outside air, an interchange must take place. The warm and lighter air inside 
passes out, and the colder and heavier atmosphere outside rushes forcibly inwards. 
Thus a system of natural movements of the air exists; and in the institution of ordi- 
nary non-mechanical ventilation these movements are not only utilized, but require, as 
a matter of fact, to be taken always into consideration." 



134 ACADEMIC PHYSIOLOGY. 

and is deflected downward toward the opposite side of the 
room, thus causing a draught. For the purpose of inter- 
cepting dust, and to divide the entering air into a large 
number of small currents, wire gauze should be placed on 
the outer side of such openings. Such are a few of the 
most simple methods of natural ventilation. For others 
the student is referred to more elaborate treatises on 
ventilation. 

17. The subject of air-outlets in connection with the 
foregoing and other methods of ventilation, is a difficult 
one. In dwelling-rooms, the chimney, if there be one, 
is regarded as affording a sufficient outlet for foul air. It 
is therefore well to bear in mind that, if reliance is to be 
placed on the chimney as an exit for impure air, the open- 
ing leading into it should never be closed. A valve 1 de- 
signed to serve as an exit for impure air may be placed in 
the wall near the ceiling, and open into the chimney. This 
light metal valve is so adapted that it swings toward the 
chimney-flue when the pressure of air from the room into 
the flue is sufficient ; but when the pressure from the 
chimney into the room is the more powerful, the valve 
closes and prevents the ingress of smoke or air. 

A more effective plan is to have a separate tube or 
shaft, divided longitudinally from top to bottom by a par- 
tition, and having openings from each of its sections into 
each room, near the ceiling, the shaft to extend beside the 
chimney and terminate above the roof. If the doors and 
windows are kept closed, a current of the outer air de- 
scends into the rooms continuously on one side of partition, 
and a current of impure air ascends from the room con- 
tinuously on the other side of the partition. If the tube 
be of proper size the air in the room is kept pure. 

Arnott's valve. 



RESPIRATION. 1 35 

18. Artificial Ventilation. — In many instances, as in large, 
crowded buildings, none of the methods of natural ven- 
tilation are sufficient to provide a constant supply of fresh 
air, and it therefore becomes necessary to employ what is 
known as artificial ventilation, in which air is forced in 
and out by apparatus driven by steam or electricity. Of 
the methods employed in artificial ventilation, the most 
common are those by propulsion and by aspiration. By 
the former method, fresh air is driven into the building 
and foul air allowed to escape by shafts or flues ; and by 
the latter, the impure air is drawn out of the building, and 
fresh air allowed to enter and take its place, after having 
been previously warmed, if required. In case revolving 
fans are used, they are caused to revolve at an immense 
rate by stationary engines, by electricity, or by other mo- 
tive power ; and by their employment air can, in one 
instance, be driven out of a building, or, on the contrary, 
may be forced into it through tubes. Such means are 
resorted to in various hospitals and other large buildings. 

19. Quantity of Air Required. — Experiments have shown 
that whenever the carbonic acid gas in the air of occupied 
apartments exceeds that in the outer or pure air by 2 
parts in 10,000 of air, the air of the apartments becomes 
unfitted for breathing. In other words, the amount of 
air-impurity which renders air unfit to be breathed is 
equivalent to .2 of a cubic foot in 1,000 cubic feet of air. 
As each person exhales, on an average, about .6 of a cubic 
foot of carbonic acid in an hour, it is evident that the air 
of a room containing 1,000 cubic feet must be diluted by 
the admission of three times the quantity of air, or 3,000 
cubic feet, if the carbonic acid breathed out is to be re- 
duced to proportions safe for continued breathing. As- 



I36 ACADEMIC PHYSIOLOGY. 

suming that each person is provided with 1,000 cubic feet 
of space, the air should be renewed three times per hour ; 
with 750 cubic feet of space, the air should be changed 
four times per hour; with 600 cubic feet, every twelve 
minutes, and so on. The rapidity with which the air be- 
comes impure is thus seen to be very great, the smaller 
the space the more rapid the contamination. 

20. In the foregoing statements, the burning of lights 
has not been taken into account. It is estimated that an 
ordinary gas-burner, consuming three cubic feet of gas 
per hour, destroys the oxygen of twenty-four cubic feet 
of air and gives off six cubic feet of carbonic acid gas and 
other impurities. It will therefore be seen that the im- 
poverishment and contamination of the air in lighting and 
heating rooms is a highly important consideration in view 
of the requirements of ventilation. Fortunately, the 
electric light removes one of the most prolific sources of 
air-impurity in rooms and dwellings. 

21. Removal of Refuse Matters. — A chapter treating of 
ventilation and failing to consider the related topic of the 
removal of waste or refuse matters from the vicinity of 
habitations, would be manifestly incomplete. The maxim 
that "dirt is only matter in the wrong place," states an 
important truth; and the removal of this wrongly-placed 
matter is essential to healthy existence. A cleanly house, 
with wholesome surroundings, is as necessary to health as 
cleanliness of body. The removal and proper disposal of 
waste matters owes its importance to the fact that, when 
people are crowded together in large numbers, as in cities 
and large towns, refuse matters accumulate enormously, 
and become a menace to publie health when they are not 
immediately and effectively disposed of by sewers or 



RESPIRATION. 137 

otherwise. When improperly treated, refuse and foul 
matters are common sources of air-impurity and water 
pollution ; and a large proportion of epidemic and other 
diseases is undoubtedly due to carelessness in the per- 
formance of the duty of removing waste matter, garbage, 
etc. Typhoid fever, cholera, diphtheria, and other deadly 
diseases, are caused and fostered by carelessness in the 
removal of decomposing animal and vegetable matter, and 
are found to disappear when such matter is carefully 
treated and promptly removed from the vicinity of human 
dwellings. 

22. Cesspools. — The disposal of waste matters by means 
of pits, called cesspools, has always been seriously objec- 
tionable because the pollution of the water in wells is 
frequently caused by such accumulations. Not only is 
the cesspool a danger in itself when, as is often the fact, 
it is situated near the house; but some of its contents are 
liable to soak into the soil, and thus pollute wells. Nu- 
merous instances have been reported in which epidemics 
have been clearly traced to the drinking of water which 
had been polluted by the contents of cesspools. 

23. Where such receptacles form the only convenient 
means of disposing of refuse matters, their construction 
should be intelligently and carefully supervised. The 
cesspool should be perfectly tight in order that its liquid 
contents shall not filter through its sides into the sur- 
rounding soil ; and its bottom should slope decidedly 
toward one side in order that the contents may be readily 
removed, when necessary, by pump or siphon. A venti- 
lator should be provided ; and if a soil-pipe runs into the 
pool from the house, it should be ventilated, " trapped," 
and should not be connected with other drains from the 



I38 ACADEMIC PHYSIOLOGY. 

house. In fact, all drains leading from the house should 
be provided with effective " traps " to prevent the foul 
gases generated in the cesspool from being carried into 
the house. The agents of protection against sewer gas 
are efficient ventilation of house-drains and well-con- 
structed " traps." 

24. Unless absolutely unavoidable, no drain should be 
located under the basement of a house. Leakage from a 
disconnected or otherwise defective basement drain satu- 
rates the soil, and, by giving off foul gases, in time ren- 
ders a house a hot-bed of disease. Whenever a drain 
beneath the basement becomes necessary, great care 
should be exercised in making it perfectly water-tight and 
air-tight. Finally, " definite arrangements for the period- 
ical clearing and cleansing of the receptacle (the cesspool) 
should be included amons: the laws of the household." 

25. Sewers. — The necessity for providing means of dis- 
posing of slops and other liquid refuse matters from 
houses and factories, in populous towns and cities, 
brought sewers into use. Sewers usually consist of stone- 
ware pipes leading into larger tunnels built of brick and 
cement, which convey and discharge the sewage matter into 
a river, into the sea, or into tanks. In the latter case vari- 
ous methods of utilizing the sewage for the enrichment of 
the soil have been devised. 

26. In consequence of the offensive and dangerous nature 
of their contents, the proper ventilation of sewers and 
frequent flushings with water are imperatively necessary. 
The ventilation of sewers tends to lessen the danger of a 
backward flow of sewer gas into houses, through the 
house-drains. The usual method of ventilating sewers is 
by means of openings in the streets, covered by gratings. 



RESPIRATION. 1 39 

If sewers are well constructed and kept clean, foul gases 
are not formed in considerable quantities; but if badly 
constructed and not kept clean, it is far better that the 
gases formed should escape into the open air than find 
their way into houses through the drain-pipes. 

27. At the connection between the house drain-pipe and 
the main sewer, there is usually placed a water " trap," 
which, whatever its special shape, is essentially a bend or 
elbow in the pipe that will hold water, the water so held 
being intended to serve as a barrier against the passage of 
foul air from the sewer. Other traps are, or should be, 
placed beneath sinks, set wash-bowls, bath-tubs, etc., for 
the same purpose. Water-traps are, however, not to be 
relied on alone ; they frequently form receptacles in which 
solid matter lodges and decomposes, and they usually con- 
tain foul water. Here again, personal care becomes an 
important factor ; and unless the traps are frequently 
flushed with pure water and all solid matter removed, de- 
composition goes on in them continually and foul gases are 
produced, " so that they become manufactories of foul air." 

28. It is very important to provide means of ventilation 
for the house-drain, and this is usually done by connecting 
a four-inch pipe with the drain (at the farthest point from 
the main sewer) and extending it up through the house, 
higher than the edge of the roof. In addition to this an 
inlet opening should be made in the drain between the 
house and the water-trap' through which a current of air 
can enter the drain-pipe and pass out at the roof. 

29. Solid matters that cannot be disposed of by means 
of sewers are collected, and, if combustible, are burned 
in immense retorts, or are otherwise removed from the 
vicinity of human habitations. 



140 ACADEMIC PHYSIOLOGY. 

30. In all contagious diseases, such as small-pox, diph- 
theria, scarlet fever, cholera, etc., slops and all other refuse 
matters should be disinfected, in order to destroy the 
bacilli or germs of the disease, before being cast into 
drains or otherwise removed. Fumigation of the room 
and disinfection of all its contents are equally necessary, 
and for the same reason. 

31. Effects of Alcohol and Tobacco. — Alcohol, on entering 
the blood, absorbs water from the corpuscles and shrinks 
them, thus reducing their capacity as carriers of oxygen 
and carbonic acid, and diminishing oxidation and the 
prompt and complete elimination of waste products. In 
these ways the habitual use of alcoholic drink interferes 
with the purposes of respiration. Again, by its effects 
on the blood, blood-vessels, and nerves, it thickens the 
tissues of the lungs, thus causing obstruction of the cir- 
culation and Congestion. One fatal form of lun°: disease 
caused by alcohol is known as "rum consumption." 
Pneumonia is most frequently incurable and fatal in per- 
sons addicted to alcoholic drink. 

32. The smoke of tobacco contains many fine particles 
which are inhaled and lodge in the air-passages, creating 
irritation. In the smoking of cigarettes the smoke is 
usually inhaled, and the poisonous products of the com- 
bustion of tobacco are thus most readily and quickly 
absorbed into the system. As cigarettes are more likely 
to be used to excess than tobacco in other forms, they 
are most objectionable and injurious. Tobacco is injuri- 
ous to the voice from irritation of the mucous lining of 
the throat. 



SUGGESTED POINTS FOR QUESTIONS. I4I 



Suggested Points for Questions. 

Chapter XIII. — 1. Refuse matters separated from the blood — organs 
engaged; lungs' principal office. 2. Double office of lungs; oxygen vitally 
necessary — absorbed. 3. Respiration defined — inspiration, expiration. 4. 
Respiratory organs — location, names; motive power. 5. Interchange of 
oxygen and carbonic acid, etc. 6. Larynx — location, structure, vocal cords, 
Adam's apple; glottis, epiglottis — action of; strangulation from food. 7. 
Trachea — location, structure; mucous membrane — cilia and their functions. 
8. Bronchi, comparative size, branches; air-cells; structure of smallest air- 
tubes — closure. 9. Lungs — location, form, separation; elastic nature, 
tissues, pleura. 10. Lobes of lungs; lobules and vessels. 11. Venous 
blood carried to lungs — pulmonary arteries and branches; capillaries and 
air-cells — nature; oxygen entering the blood, gases passing out; blood 
change; pulmonary veins — functions. 12. Thorax a closed box — structure; 
capable of enlargement. 13. Action of respiration — diaphragm, inter- 
costal muscles; inspiration and expiration described. 14. The lungs a 
bellows; lungs never empty. 15. Tidal air — amount. 16. Stationary air 

— amount; supplemental air — amount. 17. Residual air — amount. 18. 
Ordinary quantity inspired; complemental air — amount. 19. Interchange 
effected by stationary air — explanation. 20. Difference between inspired 
and expired air — gases, temperature, moisture. 21. Rapidity of respiration. 
22. Quantity of air respired in 24 hours — oxygen absorbed, carbonic gas 
given off; breathing in a close room whose dimensions are 7 feet — result; 
asphyxia. 23. Necessity of ventilation impressed. 24. Diaphragmatic and 
costal breathing — breathing of sexes compared. 25. Breathing chiefly by 
upper ribs — effects; corset compression — effects on breathing. 26. Bene- 
fits of deep breathing. 27. Breathing of gymnasts, singers, etc. 28, 29, 30. 

— Respiratory sounds — nature, cause indicative to physician. 31. Atmos- 
pheric pressure and respiration — breathing in elevated regions — rapidity. 
32. "Mountain sickness" — cause, symptoms. 33. Acclimated to rarefied 
air — effect on different persons. 

Chap. XIV. — 1 . The atmosphere ; effects of impure air in general — 
germs of disease. 2. Composition of air; essential constituents; accidental 
components — increase of. 3. Oxygen — quantity, vital principle of air. 4. 
Nitrogen — nature, office. 5. Chief of accidental constituents — effects of 
increase, sources of; imperfect combustion. 6. Animals and plants in rela- 



I4 2 ACADEMIC PHYSIOLOGY. 

tion to oxygen and carbonic acid. 7. Watery vapor in air — variations, vapor 

of breath — amount. 8. Ammonia in air and breath. 9. Ozone nature, 

where present. 10. Dust in air — kinds, sources, effects on organs. 11. 
Mouth-breathing; nose-breathing. 12. Use of respirator — dust-filter, bene- 
fits of. 13. Bacilli — nature, where present; disinfection. 14. Death from 
tainted air — logic. 

Chap. XV. — i. Object of ventilation. 2. Air in cities and occupied 
rooms — nature of. 3. Oxygen exhaustion — breath, lights, fires; re-breathing. 
4- Twofold object of ventilation. 5. Scientific ventilation — calculations 
involved; difficulties of adapting methods. 6. Neglect of provision in dwell- 
ings ; ventilation among ancients, etc. 7. Principles and means of ventila- 
tion — currents, fires, fans, etc. 8. Artificial methods of ventilation — 
indispensable locally. 9. Requisites of effective ventilation —entrance, exit, 
distribution. 10, 11, 12. Natural ventilation — wind, unreliable; movement 
caused by varying temperature — nature. 13, 14, 15, 16. Methods of venti- 
lation —inlets and outlets located — philosophy of; sub-division of current, 
direction; window apparatus — board inserted, sash perforated, pivot sash; 
opening through wall — location, fixtures, dust intercepted. 1 7. Air outlets — 
chimney-valve,- partitioned shaft, currents moving. 18. Ventilation by pro- 
pulsion and aspiration — apparatus. 19. Quantity of air required —propor- 
tion of carbonic acid; number cubic feet of air per person and renewal. 20. 

Lights and fires and air impoverishment. 21. Removal of waste matters 

importance, disease result of negligence. 22, 23. Cess-pools — source of 
danger, pollution of air and water; proper construction, ventilation, traps, 
connections. 24. Basement drains dangerous, periodical cleansing of pools. 
25, 26, 27, 28, 29. Sewers — construction, discharge, ventilation, traps for 
sewer-gas in waste pipes, flushing, house-drain ventilation and its importance, 
disposal of solid refuse. 30. Disinfection and destruction of bacilli of con- 
tagious diseases. —31, 32. Effects of alcohol and tobacco — shrinking of 
corpuscles, diminished oxidation, thickening of tissue of the lungs, production 
of "rum consumption." Tobacco — inhaled particles, effects of cigarette- 
smoking, tobacco and the voice. 



NUTRITION AND DIGESTION. 



CHAPTER XVI. 



NUTRITION. 



1. Necessity of Food. — Particles of our bodies are being 
constantly worn out, and are being continually carried out 
from the various tissues by the organs of excretion, the 
lungs, skin, kidneys, etc. New material must be intro- 
duced to replace the waste of tissue and maintain the nor- 
mal phenomena of life. Food is material by which the 
waste of the body may be repaired and the bodily sub- 
stance renewed. 

2. In addition to its primary use in renewing the sub- 
stance of the body, the food also acts as fuel in supplying 
material which, when duly burned (oxidized) in the body, 
maintains the bodily heat, and supplies energy, or the 
power of life and action. However, these latter offices of 
food are essentially included in the statement that food is 
matter by which the body repairs its losses, renews its 
substance, and maintains its life. 

3. Hunger and Thirst. — Hunger and thirst imperiously re- 
mind us of the unceasing necessity of repairing loss which 
the body sustains through the actions of life. Hunger, 
Nature's demand for building material and heat-making 

*43 



144 ACADEMIC PHYSIOLOGY. 

substances, may be withstood for a time which varies 
according to age and individual strength ; and while it is, 
at first, simply an agreeable sensation, it soon becomes a 
torture, "a succession of atrocious pains," and physical 
destruction soon follows. 

4. Thirst is, on the contrary, a sensation somewhat dis- 
tressing from the first, and it cannot be endured as long 
as hunger. It implies a privation of all liquid aliment, 
and exhaustion or death ensues much sooner from thirst 
than from hunger. It has been estimated that the length 
of time a man can exist without solid food and drink is 
about seven days. If water alone be supplied, life may be 
prolonged for many days, there being cases known in 
which men have lived twenty days or more on water 
alone. 

5. Classes of Food-stuffs. — Any substance which, when 
taken into the body, sustains and nourishes it, or, by 
being burned within it, generates regular heat and energy, 
is a food. All vegetable and animal food-substances con- 
tain three or four of the elements, carbon, hydrogen, oxygen, 
and nitrogen ; and other elements are plentifully supplied 
by water and by inorganic, or not-living, substances, such 
as salts of certain alkalies, earths, and metals. In ulti- 
mate analysis, the human body also proves to be com- 
posed of the same four elements, plus water, and the 
same saline matters, etc., as are found in the food. Foods 
are of different classes, and differ in nutritive properties, 
according to the proportions, arrangement, or absence of 
any of these elements in each. And yet it should be 
stated that a number of conditions that remain to be 
noticed influence the nutritive value of food. Food-stuffs 
may be divided into the following-named groups : — 



NUTRITION. 145 

(a) Proteids, or nitrogenous food. 

(b) Fats, or oils. 

(c) Amyloids, or starches. 

(d) Minerals, — water, etc. 

6. 1 Proteids, or Nitrogenous Foods. — Nitrogen is a gas 
which forms nearly four-fifths of the air ; and it has been 
shown by chemistry that this substance also exists in 
another form, which may be termed solid, in every living 
animal and vegetable body. That is to say in regard to 
our bodies, if a part can feel as a nerve, think as a brain, 
contract as a muscle, or see as an eye, it contains nitro- 
gen. This substance, nitrogen, is one, and perhaps the 
most important, of the elements of food and physical 
bases of life. " When we recollect that the blood, mus- 
cles, and all the vital organs contain proteids as their 
chief constituents, we can understand the importance of 
taking food rich in one or more members of this group." 
Deprive an animal of food containing nitrogen, and it 
will ultimately starve, no matter how abundant the supply 
of other food-elements. 

7. During the daily action of the body, nitrogen is 
always passing off from it, and hence must be replaced 
daily. We do not obtain from the air, by breathing, the 
nitrogen required to renew our tissues ; it appears that 
we gain no nitrogen in that way, and that we gain it only 
by food. The food which contains this nitrogen, more or 
less abundantly, 2 is called nitrogenous food, proteids, or 
albuminoids. 



1 Pro'te-id, one of certain nitrogenous principles (albumen, gluten, fibrin, casein, 
etc.) forming the chief solid constituents of blood, muscles, etc., of animals, and occur- 
ring in almost every part of vegetables. 

2 The amount of proteid in meat is from 15 to 23 per cent ; milk, 3 to 4 ; pease 



I46 ACADEMIC PHYSIOLOGY. 

8. The chief nitrogenous or proteid substances are albu- 
men, as the white of an egg, etc. ; casein of milk ; fibrin of 
meat and vegetables ; gluten of grains and flour ; and 
legumin of pease, beans, etc. The similarity of these 
substances, animal and vegetable, is quite remarkable. 
Which, then, of all these will feed the body with the 
necessary nitrogen ? The answer is, " They will all do it, 
and so perfectly that, if we have enough of any nitroge- 
nous food (and take also proper quantities of non-nitro- 
genous food), the body will retain its strength through a 
due repair of its tissues." The old controversy as to the 
respective merits of animal and vegetable food has lost 
much of its significance. Both these kingdoms supply 
nitrogenous foods which man can use, and with any of 
them may attain the highest physical and mental develop- 
ment. 

9. Fats, orOils. — There are substances, equally entitled 
to be called foods, which contain no nitrogen. Fat, or 
oil, is a food, and a very important one ; and all nations 
take this, in greater or less quantities, in some form. 
We take it in the fat of meat, or in butter, milk, and 
other articles of food. The Hindoo has his clarified but- 
ter, or a vegetable oil; many African tribes take it in the 
form of vegetable oil (olive, palm, etc.) ; some of the peo- 
ple of the far North take it as seal or fish oil. The quan- 
tity varies according to the temperature of the region, 
being larger in cold climates, or in winter, than in warm 
climates, or in summer ; and it is an indispensable food. 
Fatty articles of diet are chiefly employed in the animal 

and beans, 23 to 27 ; grains and flours, 8 to 11 ; bread, 6 to 9 ; potatoes and greens, 
1 to 4 ; and the white of an egg, which is nearly pure albumen, contains 15 per cent 
of nitrogen. 



NUTRITION 147 

economy to sustain the heat of the body by their combus- 
tion. While they are especially rich in the two com- 
bustible substances, carbon and hydrogen, they contain 
much less oxygen than the amyloid, or starch group, 
and therefore form the highest grade of heat-making 
food. 

10. Liebig and other modern chemists advance the 
theory that non-nitrogenous foods do not nourish the 
tissues, but simply supply carbon for combustion and con- 
sequent evolution of heat ; and this idea has been taught 
by physiologists until recently. While the tissues of the 
body are, without doubt, mainly constructed and repaired 
by the nitrogenous group, recent observations and ex- 
periments have shown that the fats and starches not only 
evolve heat, but no inconsiderable force also. 1 

11. The Amyloids, or Starches. — The third group of food 
substances comprises starch, and the various forms of 
sugar, gums, etc. While rich in other elements, they con- 
tain no nitrogen. We obtain from this group much the 
largest quantity of our food ; and its members, one and 
all, are products of vegetable life. Found largely in 
wheat, oat-meal, corn, rice, arrowroot, potatoes, etc., they 
are very important, and contribute to the bodily force and 
production of animal heat. The starches, entering largely 
into bread and all of the cereal grains, are quite certain to 
be taken in sufficient quantity where these are used for 
food. In potatoes, which are a valuable protective against 
scurvy, there is a large quantity of very digestible starch. 
It is a peculiarity of starch that it is easily converted into 

1 However, all the elements of nutrition, whether heat-forming or tissue-forming, 
are so sufficiently distributed throughout those portions of both the animal and vege- 
table kingdom which we use as food, as to cause, usually, no great or practical diffi- 
culty in nutrition, etc. 



I48 ACADEMIC PHYSIOLOGY. 

sugar by the processes of digestion, as will be explained 
in a succeeding chapter. 

12. Water and other Mineral Foods. — Water constitutes 
about seventy per cent of the adult body. It forms the 
greater part of the blood, and serves there as a carrier of 
other substances which it holds in solution or in suspen- 
sion. It forms a portion of all the tissues of the animal 
body, and exists as a component part of every kind of 
vegetable life. Our bodies constantly lose water by 
evaporation from the skin, exhalation from the lungs, and 
excretion from the kidneys, etc., and this loss must be 
compensated by the drinking of water and by taking 
foods which contain it in large quantity. Meat, equally 
with the muscles of our bodies, is about 75 per cent 
water ; milk about 85 ; fruits and vegetables 70 to 90 ; 
and bread about 35. Only a small quantity of water is 
necessary as a drink under ordinary circumstances, pro- 
vided that our diet and voluntary habits are physiologically 
correct. The vast quantity taken into the system may 
sometimes be accounted for through the thirst-making 
effects of concentrated food, excess of salt food, spices, 
etc., and of alcoholic drink. It is indispensable to per- 
fect health that water to be drunk, or to be employed in 
cooking, should he pure. (See chapter upon drinks.) 

13. Mineral Salts, etc. — About seventy per cent of the 
bone of an adult is mineral matter, the greater part being 
phosphate of lime ; and the carbonate of lime and phos- 
phate of magnesium are found in less quantity. The 
blood, and the muscles and other tissues, contain salts of 
potash and soda, and also iron in small quantity. These 
inorganic matters, essential to the growth and nutrition of 
the body, are found in the various articles of food, both 



NUTRITION. 149 

animal and vegetable ; and hence certain mineral elements 
are not usually taken separately as food. In cases of dis- 
ease, as when the system appears to require more of any 
of them, they are taken as medicines. The ''rickets" in 
children indicates a lack of some mineral element in the 
bones. 

14. Common salt (chloride of sodium) is one of the 
most important mineral foods. It is not generally found 
in sufficient quantity in the animal and vegetable foods as 
supplied by nature, and is therefore added separately as a 
condiment. The natural craving for it attests its value ; 
it improves the flavor of food, sharpens the appetite, and 
improves digestion. In countries where salt is scarce, it 
is sold at fabulous prices ; and it is related that certain 
African tribes exchange gold for salt, ounce for ounce, 
and that " brothers will sell their sisters, husbands their 
wives, and parents their children, for salt." Deer and 
other animals sometimes travel hundreds of miles in 
search of "salt-licks." It has been found that when 
cattle, horses, etc., are deprived of salt, their coats be- 
come rough, their spirits dull, and that they do not thrive 
well ; i.e., they lose health and strength. 

15. Necessity for a Mixed Diet. — In most instances, no 
single article or single class of food is complete in its 
composition, there being usually one or more of the essen- 
tial elements of a properly balanced food wanting. Thus, 
meat, while abounding in nitrogenous and fatty substances, 
is deficient in amyloids or starches. Vegetables, on the 
contrary, are usually rich in starch and sugar, but deficient 
in nitrogenous elements. 1 To illustrate : Meat taken alone, 

1 For this reason, foods poor in certain elements should be taken with other food 
rich in these constituents. 



I50 ACADEMIC PHYSIOLOGY. 

or mainly, supplies an excess of nitrogen ; and in order to 
obtain from meat a due amount of other elements, we 
should have to take several times the amount of nitrogen 
necessary for healthful nutrition, and, in the words of 
Huxley, " charge the system with imperfectly assimilated 
compounds, and wrongly changed products of decomposi- 
tion, which produce a gouty state of the constitution." 
On the other hand, bread is deficient in both nitrogen and 
fat ; and hence in order to obtain the proper amount of 
these by bread alone, it would be necessary to eat a very 
large quantity of it, and, by so doing, receive more than 
enough of other elements, or else starve the muscles, etc., 
from lack of nitrogen. Again, if the saline elements are 
withheld, softening or deformity of the bones is the legiti- 
mate consequence. Instances of excess or of deficiency 
in food-elements might be multiplied. 1 Hence, the system 
needs and craves a varied diet. Confinement to a single 
alimentary principle, or to any one class of them alone, 
will generally result in loss of appetite and in disease. 

16. It should be understood also, that nutriment may be 
of so concentrated a nature as to make its digestion diffi- 
cult or impossible, and that the value of an article of food 
does not depend entirely upon the amount of nutritious 
matter it contains. In order to perform its work well, 
the stomach requires a certain amount of distention, and 
therefore a certain volume or bulk is required in the food ; 
hence, very nutritious, concentrated food is generally 
most valuable when mixed with less concentrated or more 

1 " If one should attempt to live upon potatoes only, the weight of the food that 
he would have to take each day in order to get the minimum quantity of proteids 
upon which life could be sustained would not be less than ten pounds. . . . This 
would lead to great distention of the digestive organs, and render one dull and 
stupid." — Dr. V. C. Vaughan in ' Healthy Foods,' etc.'' 1 



NUTRITION. 151 

bulky food. And, finally, if any essentials in food be 
lacking, the system soon feels it ; and a person may re- 
cover from a temporary disturbance of nutrition by a 
simple change of diet, the necessity for which is often 
indicated by a longing for particular articles of food which 
contain the lacking ing -edient. 

17. Proportion of Food-elements and Quantity of Food. — Sani- 
tarians have devoted much time and observation to the 
effort to determine the proper quantity and proportions of 
the different food-stuffs required to maintain an average 
person in health. The results of these observations are, 
briefly stated, as follows : " A healthy, full-grown Ameri- 
can, doing a moderate amount of work, requires daily 
about four and one-half ounces of dry nitrogenous, three 
ounces of fatty, and fifteen ounces of sugary and starchy 
food, besides an ounce of saline matter. That is to say, 
in order to retain his full strength and weight, he must 
eat and thoroughly digest, every twenty-four hours, rather 
more than a pound of meat and eggs, about two pounds 
each of bread and potatoes, or their equivalent in other 
starchy and saccharine foods, with nearly a quarter of a 
pound of butter, lard, and suet." 1 Under ordinary cir- 
cumstances, the penalty for taking less than this amount 
is loss of flesh and strength ; and, on the other hand, the 
results of excess are derangements of the stomach, liver, 
and intestines, by overloading them, and, consequently, the 
production of dyspepsia, biliousness, diarrhoea, or consti- 
pation, with the train of evils that attend them. 

18. And yet, the varying conditions under which we live 
should diminish or increase the amount and govern the 
character of our food. Exercise or labor, the influence of 

1 " Long Life and How to Reach It," by Dr. J. G. Richardson. 



152 ACADEMIC PHYSIOLOGY. 

climate, etc., are among* the most important modifying 
conditions. A person engaged in hard muscular labor 
may require one-fourth more, while another of sedentary 
employment or habits may require less than the quantity 
mentioned. It has been estimated that "as a rule, women 
need about nine-tenths the nourishment required by men, 
boys of sixteen about the same as women, and children of 
ten years half as much as adults require." 



CHAPTER XVII. 

VALUES OF ARTICLES OF FOOD. 

1. Vegetable Foods. — The cereal grains most commonly 
used for food in the United States are wheat, rye, oats, 
corn, and rice. Their most important food constituents 
are starch, nitrogenous substances (gluten, etc.), and 
small amounts of fat, sugar, gum, and mineral substances. 
The leguminous seeds most used are pease and beans, both 
of which are richly nitrogenous. 

2. Wheat, a leading article of vegetable food, is raised 
in preference to all other grains wherever it can be read- 
ily cultivated. It is rich in nitrogenous matter, fat, and 
salts, and is considered the most nutritious of the cereals. 

3. Rye does not differ greatly in its composition from 
wheat ; but the gluten of rye is inferior in quality to that 
of wheat. Rye is much used in Russia, Northern Ger- 
many, and Scandinavia, but not very extensively in this 
country. This grain is liable to become diseased ; and 
spurred rye or ergot (a narcotic poison) has been the 



NUTRITION. 153 

cause of several epidemics of poisoning in Europe, the 
rye-bread eaten having been made from diseased grain. 
The amount of sugar contained in rye has caused it to be 
extensively used in the manufacture of whiskey, beer, 
etc. 

4. Oat-meal is richer in fat than wheat or rye, and is a 
highly nutritious article of food. Formerly used almost 
exclusively in Scotland, it is now being largely used in 
this country. Its cheapness and nutritive properties 
should commend it everywhere. 

5. Corn-meal or Indian-meal is used largely in our 
Southern States. " Prepared as the people there know 
so well how to prepare it," it is a very valuable food. It 
contains, however, but little gluten, and will not make 
good fermented bread unless it is mixed with wheat or rye 
flour. Hominy is a preparation of corn coarser than 
meal. Corn is especially rich in sugar and starch. The 
greater part of its nitrogenous matter is vegetable fibrin. 

6. Rice is a grain of Asiatic origin ; and although it is 
the chief food of the swarming millions of China and 
India, it is the least nutritious of the grains here men- 
tioned. It is not rich in proteids and fats ; and as its 
heat -producing properties are not great, it is well adapted 
for use in warm climates and during our warm summers. 
It is easily digested, and hence is valuable to the sick. 
It contains so little nitrogen that large quantities of it 
must be eaten in order to obtain that necessary element, 
if eaten alone, and hence it is usually prepared with 
milk, etc. 

7. Barley, though largely used in Northern Europe, is 
not extensively employed in this country. It is less nu- 
tritious than wheat, containing only about one-third as 



154 ACADEMIC PHYSIOLOGY. 

much gluten, but nearly an equal quantity of sugar and 
starch. 

8. Pease and Beans belong to the leguminous 1 seeds. 
Though similar in constituents to the cereals, they con- 
tain much more nitrogenous matter than any other vege- 
table food. While the nitrogenous matter of the cereals 
is principally gluten, that of pease and beans is casein. 
Gluten, however, is more easily digested than casein, and 
hence pease and beans frequently cause disturbance in the 
stomach and bowels. In the green state they are more 
easily digested than when dried ; and when dried they 
require long and thorough boiling. They should be 
soaked for several hours before they are cooked. Their 
nutritive value is considerable ; but on account of their 
difficult digestion, they should not be taken in large quan- 
tities. Their deficiency in fat is made good by serving 
them with bacon and other fatty articles of food. 

9. Potatoes are probably of more nutritive value than 
any other article of food which grows under the surface 
of the ground. Originally natives of South America, 
they were not generally cultivated in England till the 
middle of the eighteenth century. They are found 
abundantly in the wild state in Chili and Peru. While 
potatoes contain only about twenty-five per cent of solids, 
and are not rich in nitrogenous matter and fat, they will 
continue to be one of the most valuable of foods. The 
deficiency in nitrogen and fat is made up by cooking pota- 
toes with fat, meat, and other foods. Potatoes are agree- 
able to the taste and are easily digested ; " new " potatoes 
are usually not so easily digested as old, mealy ones. In 
order to retain the salts, potatoes should be cooked with 

1 Le-gu' mzn, a principle obtained from the seeds of plants ; vegetable casein. 



NUTRITION. 



155 



their skins on. When it is desired to boil them, the 
water should be hot before they are put into it. Sweet 
potatoes are similar in composition to the common or 
white potatoes. 

10. The following table gives the average composition 
of the grains, seeds, etc., which have been mentioned : — 



Articles. 


Water. 


Pro- 
teids. 


Fat. 


Sugar. 


Gum. 


Starch. 


Cellu- 
lose. 


Ash. 


Wheat 


13-56 


12.42 


1.70 


1.44 


2.36 


64.07 


2.66 


1.79 


Rye 1 15.26 


n-43 


1. 71 


0.95 


4.88 


61.99 


2.01 


i.77 


Oat-meal 


12.37 


10.41 


5- 2 3 


1.91 


1.79 


54.08 


11. 19 


3.02 
1.51 


Corn-meal 


13.12 


9.85 


4.62 


2.46 


3-38 
2.85 


62.57 


2.49 


Rice 


9-55 


5.87 


1.84 





73.00 


5.80 


1.09 
2.24 


Buckwheat 


12.63 


10.19 


1.28 




2.85 


69.30 


1. 51 




Pease 


14.99 


24.04 


1.61 






49.01 


7.09 


3.26 






Beans 


14.76 


24.27 


1. 6 1 






49.01 


7.09 


3.26 






Potatoes 


75-77 


1.79 


0.16 






20.56 


0.75 


0.97 







11. Other Vegetables, or Garden Produce. — The leading and 
most nutritious of vegetable food-articles have been briefly 
noticed ; but there are other succulent vegetables, which, 
while not highly nutritive, are used principally because 
they furnish variety, supply certain acid salts, prevent 
scurvy, and render other foods more digestible. The fol- 
lowing is a brief statement of the values of a few of 
them: — 

12. Beets are rich in sugar, containing about 10 per 
cent of it, and hence are quite nutritious. They are the 
chief rival of the sugar-cane. 

13. Turnips, carrots, and parsnips consist mainly of 



156 ACADEMIC PHYSIOLOGY. 

water (82 to 90 per cent). They are from 2 to 6 per 
cent sugar, from 5 to 10 per cent starch, and contain very 
small quantities of nitrogenous matter, fat, and salts. 

14. Cabbage and the so-called "greens" generally con- 
tain less than 5 per cent of nutritious matter ; but in 
spring their juices and salts are highly beneficial. 

15. Tomatoes are more than 92 per cent water, less than 
2 per cent starch, and about 2^ per cent sugar ; whether 
raw or cooked, they are an agreeable and beneficial food. 

16. Asparagus is one of the most wholesome and nutri- 
tious of the garden products. 

17. Rhubarb is strongly, though pleasantly, acid. As 
it is one of the earliest of spring plants, it is especially 
valuable. 

18. Cauliflower is not as nutritive as cabbage, nor so 
palatable without seasonings. 

19. Pumpkins and squash each contains only about 1 per 
cent of nitrogenous matter, 1 per cent of fat, 1 to 5 
per cent of starch, 1 per cent of sugar, and water consti- 
tutes the remainder, or greater bulk. Cooked with other 
more nutritious foods, such as butter, milk, etc., they 
make very palatable dishes. 

20. Fruits. — Estimated by their chemical constituents, 
the value of fruits as food is small ; but when properly 
ripened and well preserved, they are of great benefit to 
the system. They sharpen the appetite, make other food 
more enjoyable, and aid greatly in maintaining a healthy 
condition of the stomach and other vital organs. Fruits 
are especially valuable, and hence much used, in warm 
countries and during our summers, as they produce but 
little animal heat. The juice of fruits, consisting of 
water, sugar (from 1 to 18 percent), and acids, is the most 



NUTRITION. 157 

agreeable and valuable part ; the skins and cellular por- 
tions are not easily digested, and those fruits which con- 
tain most juice and least cell-fibre are preferable. Boards 
of Health have of late years been doing much in the in- 
spection of food supplies, but have found it almost impos- 
sible to prevent the sale of fruit unfit to be eaten. Fruit 
being a highly perishable commodity, vendors buy it be- 
fore it ripens naturally, and permit it to ripen, or, rather, 
decompose on their stands. The result is that fruit kept 
and exposed in this manner is at no time really fit to be 
eaten, as it passes from greenness to rottenness without 
being really ripe. Such fruits are extremely dangerous, 
and should not be eaten. 

21. Canned Fruits sometimes become partially decom- 
posed, and cases of serious or fatal poisoning have fol- 
lowed the eating of such fruit. Tin cans are sometimes 
used twice or oftener for the preservation of fruit, vege- 
tables, etc., and the contents of such cans are liable to 
absorb small quantities of the salts of tin and lead, which 
are poisonous. 1 

22. Confectionery. — Candy is about as valuable as an 
article of food as the sugar, starch, and gum which com- 
pose it; and, when pure, it is not injurious unless when 
taken in excess. Sometimes, however, candy is adulter- 
ated with harmful substances and poisonous coloring-mat- 
ter. Instead of containing simply sugar, flour, gum, and 
such innocent ingredients, terra alba (" white earth," or 
gypsum, which is heavy and cheap) is mixed with it ; and 

1 Dr. Vaughan recommends the following precautions relative to tin cans of 
fruit : " In buying fruit-cans, it should be observed that the ends of the cans are con- 
cave. If convex, there has probably been some decomposition of the contents with 
the evolution of gas." Again : If the cans are old and battered, they should be sus- 
pected of having been used more than once for the purpose of preserving fruit. 



158 ACADEMIC PHYSIOLOGY. 

in any considerable quantity terra alba is harmful on 
account of being indigestible. Gritty, chalky candy 
should be rejected. Green, bright-yellow, and orange 
candies may be poisonous, because the coloring agent in 
these is most frequently chromate of lead. Ultra marine 
is also harmful when used in large quantities as a pig- 
ment. White candy is probably the most wholesome. 



CHAPTER XVIII. 
value of foods {concluded). 

1. Animal Foods. — Mankind obtain a large proportion of 
their food from the animal kingdom. The quadrupeds, 
fowl, and fishes of the waters supply a great variety ; and 
there are but few parts of an animal that have not been 
more or less employed as human food, in the quest for 
variety. The alimentary principles derived from animal 
food are protein, gelatine, oleaginous, and the saccharine 
matter of milk ; in other words, fibrin, albumen, casein, 
gelatin, and sugar. They are yielded by the muscles, fat, 
cartilages, ligaments, cellular and nervous tissue, milk, 
and eggs of the animal kingdom. 

2. The lower animals eat vegetable food, and appropriate 
or build up its elements into their tissues ; and these tis- 
sues, similar in chemical elements to the flesh of man, are 
made use of as food by him. 

3. Of the food derived from animals, meat is one of the 
most important, and consists of water, mineral salts, albu- 



NUTRITION. 159 

men, fat, etc. Herbivorous animals, those which feed 
upon vegetables exclusively, are usually preferred as food 
to those which prey upon other animals. Omnivorous 
animals, which eat indiscriminately vegetables, or other 
animals, are by some believed to be inferior as food to the 
purely herbivorous ; and the carnivorous, which subsist 
upon other animals exclusively, are still more inferior. 
In the most civilized countries, the domesticated animals 
afford the principal flesh-meat. 

4. Circumstances affecting the Value of Animal Food. — The 
quality of food derived from animals may be greatly varied 
by circumstances. The age of the animal and the man- 
ner in which it has been prepared for market have a 
marked influence upon the quality and composition of the 
flesh. Very young or very old animals are less valuable 
for food than those nearly full-grown or middle-aged. 
Again, animals which have been excessively and quickly 
fattened, or stall-fed, and those which have been " slop- 
fed " with liquid preparations, the refuse matters of the 
kitchen or of distilleries, are more or less deteriorated in 
food value. 

5. The quality of meat is also affected by the manner in 
which the animal is slaughtered. All flesh contains blood, 
much of which is venous and impure from the waste and 
effete matter which is about to be expelled from it ; hence 
the slaughtering is, or should be, so conducted as to 
remove as much of the blood as possible. The Jewish 
custom of soaking meat half an hour in water, and then 
letting it lie an hour in salt before cooking, was for the 
purpose of further cleansing it of blood ; and the Mosaic 
regulations relative to the use of flesh as food were 
philosophical. 



l60 ACADEMIC PHYSIOLOGY. 

6. In all animal structures, the process of decomposi- 
tion begins soon after life is extinct ; and although the 
evidences of such change may not be offensively evident 
to the senses of taste or smell for some time, the sooner 
meat is eaten after the rigor mortis (stiffness of death) 
has left it, the better, especially in warm weather and 
when meat is not kept frozen. Some epicures have meat 
kept till it becomes tender from age, but such tender- 
ness is a condition of the first stages of putrefaction ; and 
although the article may be more easily masticated by the 
teeth, and very quickly dissolved in the stomach, it cannot 
be properly digested, nor can it be converted into pure 
blood and sound tissue. The flesh of a healthy animal 
may become poisonous from partial decomposition ; and 
hence to make tough meat tender, it is much better to 
break up its fibres by thorough pounding before cooking, 
thus making some allowance for the masticatory ability of 
imperfect teeth, or of artificial ones. 

7. The value of 'meat \ and also of other foods, is influenced 
by the manner of cooking. Proper cooking not only ren- 
ders food more agreeable to sight, smell, and taste, but by 
so doing stimulates the flow of the digestive juices and 
renders the food itself more digestible. 

8. Meats which should not be Eaten. — The following list of 
flesh-meats which should not be eaten is given by Gerlach, 
director of the Royal Veterinary School at Berlin : — 

(i) The flesh of animals which have died of internal 
diseases, or which have been killed while suffering from 
such diseases, and of healthy animals which have been 
killed by over-driving. 

(2) The flesh of animals having contagious diseases 
which may be transmitted to man. 



NUTRITION. l6l 

(3) The flesh of animals which have been poisoned. 

(4) The flesh of animals having infectious diseases, 
such as blood-poisoning from wounds, etc. 

(5) Flesh which contains parasites that may be trans- 
mitted to man, such as pork containing trichina* a micro- 
scopic insect. 

(6) All decomposing or putrid flesh. 

9. Special Properties of Meats in Common Use. — Beef ranks 
first in value of all the meats used by civilized people. 
Scientific investigation, as well as common experience in 
its use, proves that beef is most nutritious, and that a 
smaller quantity of it than of any other flesh-food will 
appease hunger. Meat from different animals of the 
same class varies in composition, flavor, and digestibility, 
as has been already intimated ; and this is also true of 
different portions of the same animal. In beef, and in 
the order in which they are mentioned, porter-house, sir- 
loin, and round steak are considered most valuable ; and 
from these the scale of values descends to neck and flank 
pieces, which are considered to be least valuable. In 
color, good beef is reddish-brown. Beef of a pale-pink 
color should be suspected as having been taken from a 
diseased animal ; and that of a dark-purple color, as being 
the flesh of an animal which has not been properly slaugh- 
tered (or not slaughtered at all), and which died without 
sufficient bleeding. Wholesome beef has little if any 
odor, at least is not disagreeable to the sense of smell. 
Meat of any kind which is wet and inelastic to the touch 
is not in good condition. 

10. Veal, the flesh of calves, is considerably less nutri- 
tious, and not as easily digested as beef. Veal from very 
young animals is unwholesome ; in some localities, the 



1 62 ACADEMIC PHYSIOLOGY. 

slaughtering and offering for sale as food of calves under 
one month old are prohibited by law. Veal, especially 
when too young, is apt to cause cramps and diarrhoea ; 
and some stomachs cannot digest it at all. 

11. Mutton, though more easily digested than beef, is 
less nutritious. From its easier digestion, mutton is better 
adapted than beef to the powers of a dyspeptic stomach ; 
and it is well known that mutton broth is especially valu- 
able as food in cases of dysentery. Lamb is less nutri- 
tious than mutton, and, like veal, it is not suitable for 
weak stomachs. 

12. Pork, for various reasons, is one of the most impor- 
tant of meats. Hogs can be fattened more easily and 
cheaply than oxen or sheep, and they usually store up in 
their structure in the form of fat several times as much of 
the food which they eat as oxen do. Pork is a heat-pro- 
ducing food, and is well adapted for use in cold weather. 
It contains less nitrogenous substance and is less nutri- 
tious than beef. Hogs are too frequently fed unwhole- 
some and unclean food, and consequently their flesh 
deteriorates proportionately in wholesomeness. Of all 
the meats, pork is the one most liable to be diseased, and 
is quite frequently infested by a minute worm known as 
the trichina spiralis. It has been found that a cubic inch 
of pork may contain nearly a hundred thousand trichinae. 
The young trichinae are hatched out in the intestines of 
those who are so unfortunate as to eat diseased pork, and 
burrow their way out into the muscles of all parts of the 
body, setting up inflammation which often results in death. 
Trichinae are not easily killed, and neither smoking nor 
salting of pork accomplishes their destruction. As their 
presence in pork cannot be discovered without the aid of 



NUTRITION. 163 

the microscope, it is never safe to eat the meat unless it 
has been thoroughly cooked. The smallest fragment from 
the interior of a ham which escapes being heated to nearly 
the boiling-point of water (21 2°) may carry a number of 
living trichinae into the stomach of one who eats it. 1 

13. Salt extracts juices from meat ; and as these remain 
in the brine, salt meats are usually less nutritious than 
fresh meats. Dried meats are, as a rule, less easily 
digested than the same meats when fresh ; but bacon and 
ham are exceptions to the rule, as, when properly cured, 
they are digested more easily than fresh pork. 

14. Fowl, or poultry, is usually more easily digested than 
the meats thus far mentioned, but is regarded as less 
nutritious. Poultry and game are less juicy than the other 
meats, and, as a rule, contain less fat. The white meat of 
fowls is more easily digested than the dark meat, but it is 
not as rich in nitrogenous matter and in flavor as the lat- 
ter. Chicken broth is more delicate in flavor and more 
nutritious than that made from beef or mutton, and is 
therefore a valuable food for the convalescent. The flesh 
of carnivorous birds is not in itself poisonous, but is gen- 
erally strong in odor and not agreeable in taste. 

15. Fish is poorer in nitrogenous elements, but richer 
in certain important salts, than the meat of warm-blooded 
animals. Fish which have red or pink flesh are richer in 
nitrogen than those whose flesh is white. Fish under- 
goes rapid decomposition, and when decomposition has 
set in is highly unwholesome. It should never be eaten 

1 " The trichina disease comes on generally with violent vomiting and diarrhoea, 
followed by high fever, with severe pains in the limbs, back, and head. For some 
time it can scarcely be distinguished from acute poisoning, or sometimes from typhoid 
fever ; but about the seventh or eighth day a peculiar swelling of the eyelids and root 
of the nose indicates the true nature of the disease," 



164 ACADEMIC PHYSIOLOGY. 

except when undoubtedly fresh. Stale fish has shrunken 
eyes, bloodless gills, and presents a withered appearance 
in general ; but as vendors sometimes resort to expedients 
to improve the appearance of stale fish, the most reliable 
test of freshness is the odor. Of the crustaceans, lobsters 
and crabs closely resemble the other fish in constituent 
elements, but are more muscular and less easily masticated 
and digested ; besides, their flesh is peculiarly inclined to 
rapid decomposition, and when eaten in this condition 
it frequently causes sickness which may result fatally. 
Clams, whether raw or cooked, are difficult to masticate 
and very indigestible. Oysters, while not very nutritious, 
are delicate in flavor and easily digested, more particularly 
so when raw. There exists a popular belief that fish is a 
food which is especially adapted to the development of 
brain and nervous structures, but its supposed advantages 
in this particular lack scientific confirmation. 

16. Milk, etc. — Milk contains representatives of all the 
classes of food, and therefore has all the elements required 
for prolonged nutrition. It should be the principal food 
of young children, and for adults it forms a palatable and 
easily digested article of diet. Some invalids cannot 
enjoy it, and some dyspeptics cannot tolerate it ; but 
exceptional cases from morbid conditions are not rules 
for healthy persons. Milk is composed about as follows : 
water, 87.5 ; casein and albumen (nitrogenous constitu- 
ents), 3.5 ; fat, 3.5 ; milk sugar, 4.8; ash (salts, etc.), 0.7 
per cent. This, however, is only an average composition, 
as no two cows yield milk which is precisely alike in chem- 
ical elements ; and milk from the same cow varies with 
the manner of feeding, quality of the food, etc. Cows 
fed in close, filthy stables, upon warm slops and other 



NUTRITION. 165 

refuse matters of distilleries, become diseased and often 
consumptive; and the " swill milk" from such animals 
is, consequently, unwholesome and disease-producing. 
" Barn-yard milk" is the name sometimes applied to milk 
yielded by unclean animals, or by those kept in filthy, 
unventilated stables. Such milk has absorbed odors which 
are plainly perceptible, and which, while they may not 
render it absolutely poisonous, make it repulsive and to a 
certain degree unwholesome. 

17. Adulteration of milk is quite common, and is accom- 
plished in several ways. The addition of water is the 
fraud most commonly resorted to, the effect of which is 
to lessen the nutritious properties of the milk. This 
adulteration can be detected usually by means of the 
lactometer (an instrument designed to test the specific 
gravity of milk) ; but even this test cannot be relied on in 
all instances, because artful and dishonest persons some- 
times increase the specific gravity of watered milk to the 
required standard by dissolving salt or sugar in it. " To 
furnish a child with watered milk is often to slowly starve 
it to death, and the person guilty of such an act should 
be treated as a criminal." — (Dr. V. C. Vaughan). In 
some States such adulteration is prohibited by law, and 
regularly authorized inspectors are appointed whose duty 
it is to examine milk and prosecute those who adulterate 
it. Watery, innutritious milk may be produced by feed- 
ing cows sloppy food, reference to which has already been 
made. Akin to the dilution of milk by adding water, is 
the removal of more or less of the cream by skimming, 
thus robbing it of nutritious properties. The greater or 
less amount of cream which forms upon milk contained in 
a tall, narrow vessel is a simple but quite effective test of 
richness. 



1 66 ACADEMIC PHYSIOLOGY. 

18. Care of Milk. —Disease Germs. — The care of milk is 
extremely important, as there are so many ways in which it 
may become contaminated, and hence dangerous to health 
and life. 1 The following precautions should be observed 
in the care of milk : (i) For the reason that milk rapidly 
absorbs gases, and because dust which falls into it may con- 
tain disease germs, it should never be allowed to remain in 
an uncovered vessel in an occupied room. (2) It should 
not be kept for any length of time in metallic vessels, 
(copper, brass, or zinc), or in earthen vessels glazed with 
lead. If the milk becomes even slightly sour, its acid may 
dissolve sufficient of the metal to render the milk poison- 
ous. (3) All vessels which have contained milk should 
be scalded with boiling water before they are used again. 
The most scrupulous cleanliness is necessary in order to 
keep milk wholesome. 

19. The different ways in whicJi viilk may become so 
infected as to transmit disease are presented briefly by 
Dr. Vacher, as follows : (1) The milk may be derived 
from a tuberculous cow. (2) It may be derived from a 
cow having a specific epizootic disease. (3) It may be 
drawn from an inflamed udder. (4) It may have under- 
gone chemical or fermentative change. (5) It may have 
become infected with the contagion of an animal dis- 
ease. (6) It may have become infected with the con- 

1 Cases of poisoning by milk occurred at one of the hotels at Long Branch in the 
summer of 1886. The investigations of the experts proved that the cause of the 
sickness was poisonous milk, and that the toxic element in it was tyrotoxicon. 
The report of the experts says : " The production of this substance was no doubt due 
to the improper management of the milk, that is, too long a time was allowed to 
elapse between the milking and the cooling of the milk ; the latter not being attended 
to till the milk was delivered to the hotel ; whereas, if the milk had been cooled 
immediately after it was drawn from the cow, fermentation would not have ensued, 
and the resulting material, tyrotoxicon, would not have been produced." 



NUTRITION. 167 

tagion of a human disease, either by germs falling into 
it, or by means of polluted water with which the milk 
was adulterated, or with which the vessels containing it 
were washed. Wide-spread epidemics of scarlet fever and 
typhoid fever have been unmistakably traced to the milk 
supply. " In one instance, cases of typhoid fever broke 
out among the customers of a certain milkman ; and when 
an investigation was held, this person admitted that his 
milk-cans had been ' washed out ' with water from a certain 
well which was proved to be infected by sewage from a 
neighboring cess-pit containing typhoid fever excrement." 
The germs of diphtheria may, in like manner, be dis- 
tributed in milk. 

20. Two preventives of miscJiief are recommended to the 
consumer : (1) To examine the milk delivered to him, and 
to reject it if it appears to be watered, or if it is streaky, 
ropy, blood-stained, or smells disagreeable from any 
cause. (2) To thoroughly boil the milk received, though 
this alters its nature somewhat. To these precautions 
may be added that of keeping the milk in covered vessels 
in closets where the air is clean and cool. 

21. Butter and Cheese. — These foods furnish the nutri- 
tious elements of milk in concentrated form. Of the fats 
used as food, butter is the most agreeable to the taste and 
most easily digested, and its food value is great. Good 
butter is free from rancid taste and odor. All butter con- 
tains casein which is derived from the milk skimmed off 
with the cream ; but as rancidity is chiefly occasioned by 
decomposition of the casein, the less it contains, the less 
liable it is to become rancid, or " strong." Butter is sel- 
dom adulterated with injurious substances, except that 
purified animal fats, butterine and oleomargarine, are 



1 68 ACADEMIC PHYSIOLOGY. 

often mixed with the poorer grades of butter. These 
adulterations, though repulsive, are not, as a rule, very 
detrimental to health. Butter, like milk, readily absorbs 
impurities; and the restaurant system of exposing butter 
to an atmosphere charged with foul matter, possibly with 
disease germs, is highly reprehensible. 

22. Cheese is very rich in nitrogenous matter and fats ; 
of these it contains an average of twice as much nitrogen 
and three times as much fat as an equal weight of meat. 
As it is a highly concentrated food, it should be taken 
only in small quantity at a time. When fresh, it is re- 
garded as good food ; but it is very liable to decomposi- 
tion, and when this sets in, cheese becomes irritating and 
indigestible. Old, strong cheese, though itself very indi- 
gestible, is known to be an aid in the digestion of other 
substances, and is taken, therefore, as a condiment ; but 
the quantity eaten should be very small. In taking cheese 
it is well to recollect the old doggerel : — 

" Cheese is a mity elf, 
Digesting all things but itself." 

23. Eggs. — These are a highly nutritious article of 
diet, and are easily digested when properly cooked. The 
white of the egg consists of water and albumen, with 
minute quantities of mineral salts and fat ; the yolk is 
about one-third fat ; in other words, the fat of an egg 
is confined almost entirely to the yolk. Eggs contain 
neither starch nor sugar, and should therefore be eaten 
with articles which contain these substances. Eggs are 
most easily digested when taken uncooked, or when 
boiled sufficiently to coagulate the white without harden- 
ing the yolk. Hard-boiled or hard-fried eggs are digested 



NUTRITION. 169 

with difficulty. In the preservation of eggs, the object is 
to prevent the 'passage through the shell of germs from 
the air which cause decomposition ; this may be accom- 
plished quite effectively by dipping eggs in mucilage and 
then packing them in salt ; or by simply packing them in 
salt alone, or in salt and lime, in these ways excluding the 
air. When eggs are put into a strong brine made of an 
ounce of table salt and ten ounces of water, the sound 
ones will sink, while the stale ones will float. 

24. Cooking. — An article upon food would be imperfect 
without a reference to the best modes of cooking, as 
cookery and digestibility are closely related. Cooking is 
designed (1) to soften the food and thus render easier its 
mastication and solution by the digestive juices ; (2) to 
develop its flavor and make it more agreeable in taste and 
odor; 1 and (3), particularly with meats, to destroy para- 
sites and disease germs that may infest it. Careless or 
unskillful cooking very frequently presents us with tough, 
dry, tasteless dishes which are as innutritious and indi- 
gestible as they are unpalatable. Good cookery is the 
practical result of centuries of experience in that direction, 
the final flower of ages of evolution. 

25. Cooking of Meat. — A chief object to be attained in 
cooking meat is the retention of its internal juices, and 
hence its nutritious elements. In all the modes of cook- 
ing meat, a high degree of heat should therefore be applied 
at first in order to quickly coagulate the albumen upon 

1 Some one aptly remarks, " The quantity of nourishment depends greatly upon 
the aromatic flavor contained in food ; and whatever is insipid to the taste is of little 
service to the stomach. Now, the difference between good cookery and bad cookery 
lies principally in the development of the flavor of our food ; articles properly cooked 
yield the whole of it ; by good cookery we make the most of everything — by bad 
cookery, the least." 



170 ACADEMIC PHYSIOLOGY. 

the surface, and thus retain the juices. Broiling, roasting, 
or baking of meats retains the juices and flavor better 
than when cooked by boiling. In these modes of cooking, 
the fire should be brisk at the beginning ; but the meat 
should not be exposed to this high heat during the entire 
time of cooking, else the fibre will be made hard and indi- 
gestible. Broiled meat is found by most, persons to be 
most easily digested. When meat is to be boiled, the 
pieces should be large and should be put into water 
already boiling; but after about ten minutes the heat 
should be lowered to a degree at which there shall be 
little, if any, perceptible boiling, and this temperature 
should be retained till the fibre is made tender. If soup 
is to be made, the meat should be put into cold water, and 
the temperature slowly and gradually raised ; the object 
in boiling being to retain the nutritious fluids, while in 
soup-making the design is to extract them. Albumen is 
instantly hardened by boiling water, while it readily dis- 
solves in warm water. Frying is the poorest method of 
cooking meat, because it drives out the natural juices and 
does not compensate for this by the cooking in lard or 
other fat. Fried meats are usually much less easily 
digested than meats prepared in the other modes men- 
tioned. In frying meat, the fat should be made very hot 
before the meat is put into the pan, and should be cooked 
rapidly and removed from the utensil immediately on 
becoming tender. The most common errors in cooking 
meat are using continuously too high a temperature and 
over-doing the cooking. 

26. Cooking of Vegetables. — Most vegetables are usually 
cooked by boiling. The chief care to be taken is that the 
boiling process be carried far enough to soften the sub- 



NUTRITION. . 171 

stance without breaking down its structure so completely 
as to cause it to dissolve in the water and be lost. When 
the boiling has softened the vegetable, it should be re- 
moved from the water before it cools, because while boil- 
ing the pores of the vegetable are filled with steam ; but 
when cooling begins, the steam condenses and the sur- 
rounding water passes in to fill the partial vacuum, thus 
causing the vegetable, particularly if it be a potato, to 
become sodden and indigestible. Potatoes, in order to 
retain their natural salts, should be boiled with the skins 
on, and should not be put into the water until it is hot. 
In baking potatoes, the oven should be moderately hot. 
Vegetables which are deficient in oils are cooked or served 
with butter, lard, bacon, or other fats. 

27. The Mixing of Bread. — Fermentation is a process in- 
volving a series of chemical changes by which the organic 
elements of vegetable substances are reduced to their 
ultimate or chemical elements ; that is, as applied to 
grains, fermentation is the decomposition of the sugar, 
and the recombination of its elements so as to produce 
alcohol and carbonic acid. The alcohol produced in bread- 
making is mostly driven off by the heat of the oven, and 
the carbonic acid gas, being retained by the tenacious 
gluten, raises or puffs up the dough. If the dough is not 
thoroughly kneaded, good bread cannot be made. If the 
yeast is not equally mixed with every particle of the flour, 
the fermentation will be unequal, and some portions of the 
bread will be heavy or compact. While the dough must 
be allowed to rise sufficiently, yet, if the fermentation is 
allowed to proceed too far, the sugar and starch will, to 
some extent, be destroyed, and acetous acid (vinegar) will 
be formed, rendering the bread sour and indigestible. 



172 ACADEMIC PHYSIOLOGY. 

When the dough has been properly kneaded, it should be 
covered with a napkin or light woollen blanket, and kept 
at about 6o° Fah. until sufficiently light. " The process 
of fermentation is arrested at a temperature below 30 , 
proceeds slowly at 50 , moderately at 6o°, rapidly at 70 , 
and very rapidly at 8o°." Unfermented bread is that 
which is rendered light by means of acids and alkalies, or 
by forcing carbonic acid gas into the dough, in the latter 
instance making what is known as " aerated bread." 

28. Baking of Bread. — All bread, whether raised or un- 
leavened, to be easily digested, must be light, dry, friable, 
and so porous as to readily absorb water. Bread is also 
comparatively indigestible if underbaked or overbaked. 
It is a common error that bread can hardly be overdone 
in baking. Its dietetic value begins to deteriorate the 
moment baking proceeds too far ; and as much care should 
be taken to remove it from the oven as soon as it is baked 
sufficiently as to have it remain till well done. When the 
crusts of a newly baked loaf are hard and thick, it is cus- 
tomary to wrap the loaf in wet cloths to soften it ; but 
this practice is objectionable for the reason that it pre- 
vents the free evaporation of such alcohol as may still 
remain in it, thus rendering the bread more difficult of 
digestion. The most important food constituents of bread 
are the same as those of the grains from which it is made, 
i.e., proteids, starches, and vegetable salts; and as the 
amount of nitrogenous matter and fats is too small for a 
perfect food, it is usually taken with meat, which is nitro- 
genous, and with butter to supply the fats ; thus with 
these additions, bread becomes a perfect food. 

29. Condiments. — In our cookery, very few simple and 
uncompounded flavors are left to us ; everything is so 



NUTRITION. 173 

mixed that only by special experiment can one discover 
what are the effects of special flavors upon the palate. 
This makes it quite difficult for us to realize the distinct- 
ness of the elements which go to make up the tastes as 
we commonly experience them. Then, too, a great many 
food articles have but little flavor of their own, and only 
a feeling of hardness or softness, or glutinousness in the 
mouth, mainly noticeable in chewing them. Thus, plain 
boiled rice is almost wholly insipid, and salt is usually 
boiled with it ; and in practice, we generally eat it with 
sugar, fruit, milk, or with some strongly flavored con- 
diment. Again, plain boiled tapioca, sago, etc., are as 
nearly tasteless as anything can be ; but milk, in which 
they are oftenest cooked, gives them a relish ; and sugar, 
eggs, cinnamon, or nutmeg are usually added by way of 
flavoring. Gelatine by itself is merely very " swallowable ; " 
and we mix sugar, lemon juice, and other flavorings with 
it in order to make it into good, tasty jelly. Condiments, 
therefore, are substances whose employment in cooking is 
for the purpose of seasoning foods. One member of this 
class (common salt) is necessary to healthy existence. 
Salt, spices, essences, vinegar, pickles, catsups, sauces, 
etc., are, in general, just our civilized expedients for add- 
ing the pleasure of pungency and acidity to naturally in- 
sipid foods, by stimulating the nerves of taste, just as 
sugar is our tribute to the purely gustatory sense ; and as 
oil, butter, bacon, lard, etc., used in frying, are to the 
sense of relish which forms a last element in our com- 
pound taste. However, while much benefit may arise 
from the use of condiments in small quantities, large or 
excessive use of them sometimes proves very injurious to 
health. 



174 ACADEMIC PHYSIOLOGY. 

30. Condiments are very frequently adulterated with 
cheaper or more harmful substances. Thus, vinegar is 
sometimes adulterated with sulphuric acid; table mus- 
tards, with tumeric ; and pepper and other spices are 
sometimes mixed with flour, starch, and ground peanut- 
shells. In order to obtain pure spices they should be 
purchased unground. 



CHAPTER XIX. 

DRINKS. WATER AND HEALTH. 

1. Physiological Offices of Water. — Water may be regarded 
as second among the primary necessities of animal life. 
It has been estimated that man can live without air from 
two to ten minutes ; without water, from three to five 
days ; and without food, from ten to fifteen days. Water 
is the instrument of change ; and nutritive substances can- 
not enter the system, nor the waste of the tissues leave it, 
unless held in solution by water. By its solvent power it 
performs these necessary offices. As water is one of the 
substances absolutely necessary for life, its purity is not 
less a requisite for health. All persons, however, do not 
know that transparent, sparkling water is not always whole- 
some ; and many believe that soft water is necessarily 
pure. Perfectly transparent waters may contain poisonous 
mineral impurities ; and while pure water may be soft, soft 
water is not always pure. Absolutely pure water can 
hardly be found, but that which is most nearly pure should 
be sought ; and sources of pollution should be watched 



NUTRITION. 175 

with great care, and all such as are preventable should be 
removed or avoided. 

2. The chief impurities of water consist of mineral 
matter-either in solution or in suspension, or both ; and of 
organic matter — vegetable and animal substances which 
find their way into it, and, by their decomposition, render 
the water unwholesome. The foreign mineral ingredients 
found in water in its natural state, modify its character 
according to their quantity and their peculiar properties, 
and give rise to the varieties known as hard water, soft 
water, sea water, and mineral water. 

3. Rain-water. — The ultimate source of all fresh water 
is the ocean, whence, by a natural process of distillation, 
vapors rise into the upper regions of the atmosphere and 
are there condensed into rain-water, which is the purest 
that nature supplies. However, in descending, rain-water 
becomes impregnated with impurities that may be floating 
in the air. These impurities in the air, above and about 
large towns and cities, consist of gases, soot, and various 
other organic and inorganic atoms. 

4. Again, rain-water becomes mixed with corrupting 
vegetable, animal, and mineral substances that are diffused 
more or less abundantly over every exposed surface in the 
neighborhood of living beings ; and hence, water collected 
from roofs usually contains such impurities, and has a ten- 
dency to rapid putrefaction. Especially is this the case if 
the roof is of wood and old, and if there are projecting 
branches of trees which deposit leaves and other debris 
upon the roof and in the gutters ; also when birds — 
pigeons, sparrows, etc. — frequent the roof. Impurities 
from pipes through which it flows (such as lead), or from 
foul cisterns, or other reservoirs in which it is stored, 



176 ACADEMIC PHYSIOLOGY. 

frequently render rain-water less suitable for drinking and 
cooking than good well-water. In all instances, the cis- 
tern or other receptacle should be kept scrupulously clean. 
A cistern should be so built as to prevent the possibility 
of water from the surrounding soil (which may be filth- 
soaked) finding its way in through the walls. Being free 
from saline matter and certain other mineral ingredients 
(lime, etc.), rain-water is excellent for washing, but is 
rather insipid in taste. When shed from clean slate or 
galvanized-iron roofs, and stored in perfectly clean and 
tight receptacles, rain-water is, practically, the best water 
for general use. 

5. River, or Surface Water. — The water of running streams 
is, in part, that which has run into them directly from the 
surface of the adjacent slopes, and in part that of the flow 
from springs, shallow or deep. As contact and consider- 
able friction with the ground take place, saline matter 
and also vegetable and animal matters are liable to be 
taken up and to become dissolved in the water of running 
streams. The extent to which the water becomes impreg- 
nated with these substances depends upon the nature of 
the strata through which it passes, and upon the condi- 
tion of the surface of the ground upon which the rain falls, 
and over which it flows into the stream. In thickly set- 
tled regions, the amount of refuse matter upon the surface 
of the ground is usually considerable, and the water col- 
lected from such sheds is unfit for drinking and cooking 
purposes. Besides, if the refuse of factories, drainage and 
sewage of towns and cities situated upon its banks flow 
into a stream, its water is rendered very impure and dan- 
gerous to health. In thickly settled countries there are 
but few rivers left from whose lower course a supply of 



NUTRITION. 177 

water for drinking and cooking should be taken. 1 That 
the water of running streams undergoes purification to a 
certain degree is undeniable ; but notwithstanding, spe- 
cific poisons have been carried long distances in rivers, 
and have still manifested their evil effects. Hence, the 
great objection to water from rivers is their general pol- 
lution. When rivers are not thus polluted, this variety of 
water is one of the least objectionable. 

6. Water from ponds> marshes, and small streams is apt 
to be impure, not having even the somewhat uncertain 
benefit of filtration through the earth to strain out 
organic impurities and the germs of disease that it may 
contain. Many attacks of ague, typhoid fever, dysentery, 
and cholera have been traced to the drinking of impure 
surface-water. The terrible epidemic of typhoid fever 
that recently resulted in the death of scores of people in 
a Pennsylvania town gave a fearful example of the harm 
that may, at any time, follow careless or ignorant pollu- 
tion of streams from which water for domestic use is ob- 
tained. In this instance, the slops from the sick-room of 
a person having typhoid fever were thrown upon the ice- 
covered banks of a stream, and thence ran into it when 
the ice melted, poisoned the water, and carried disease or 
death to all who drank it. 

7. Spring Water. — Well Water. — Subterranean waters 
used for drinking and cooking purposes are obtained from 

1 As an instance, the largest cities of New Jersey, Jersey City and Newark, obtain 
their water-supply from the lower course of the Passaic River. Only a few miles above, 
this stream receives the sewage of the large city of Paterson, and of the smaller city 
of Passaic, together with the refuse of numerous factories, dye-houses, etc. Analyses 
of the water-supply of Jersey City and Newark have proved it to be much polluted 
and unfit for drinking and cooking, and hence these two cities propose to abandon its 
use for domestic purposes. Above Paterson the waters of the Passaic are excep- 
tionally pure. 



■■■ 



I78 ACADEMIC PHYSIOLOGY. 

springs and wells. Spring-water is generally clear, spar- 
kling, and of a uniform temperature (50 ) at all seasons of 
the year, and hence has properties that commend it to the 
eye and to the palate in an eminent degree. However, 
the purity of either spring or well water depends, prima- 
rily, upon the geological formations in which their sources 
are situated. In order that such water shall be pure, its 
source must be beneath rock, or thick beds of clay, which 
prevent direct contamination from the surface of the 
ground. Springs in gravel formations may be as impure 
as shallow wells, and for similar reasons. 

8. Well-water is obtained from wells, shallow or deep. 
The water of shallow wells is really surface-water, often 
of the most impure kind. Just as a ditch collects water 
from a wet field, a shallow well drains water from the sur- 
face of the ground adjacent to it ; and if the ground is 
filth-sodden from impurities that have accumulated upon 
and within it, these foul matters dissolve in the water and 
are carried into the well. It is a great error to believe 
that when water percolates through a few feet of earth 
every harmful substance is detained somewhere in the 
soil, and does not enter the spring or well. In passing 
through filth-soaked earth, the impurity of water is in- 
creased, and not diminished. In country districts the 
water of new wells is commonly pure, and may remain so 
for a long time if cess-pools, out-closets, and stables are 
not near them, and if kitchen slops, wash-water, etc., are 
not cast upon the ground in their vicinity. 

9. In cities and towns where there are always many 
sources of pollution, — absence of proper drainage, leaky 
sewers and drains, numerous cess-pools, etc., — the ground 
becomes saturated with filth, and much foul and harmful 



NUTRITION. 179 

matter is carried into wells. A well, a cess-pool, and an 
out-closet are often found in close proximity in a small 
yard ; and it has been well remarked by an eminent sani- 
tarian, that, " If the well be a shallow one, such an 
arrangement is probably the worst, in a sanitary sense, 
that could possibly be devised." 1 

10. Deep zuells, the water of which is naturally purer 
that that of shallow ones, should have their walls so con- 
structed as to prevent the entrance of water from the sur- 
face, else the water of these may become as objectionable 
as that of shallow wells. There is a lesson that should be 
learned by all, — that there are disease and death in cess- 
pools, filth-sodden soil, and bad drainage as related to the 
water used for drinking and cooking ; and, while in the 
case of a public water-supply it is the duty of the proper 
authorities to use all possible means to prevent its pollu- 
tion, it is equally the duty of the consumer and of those 
who have the care of private wells to take due care that 
water is not contaminated on their premises. 

11. Hardness of Water. — Spring and well waters are often 
hard, and by this term is meant that they fail to make a 
lather unless a very large quantity of soap is used with 
them. In washing, hard water occasions chapping of the 
skin, great waste of soap, much extra labor, and a corre- 
sponding increase in the wear of fabrics during their wash- 
ing. The hardness of subterranean waters is commonly 
due to the presence in them of the salts of lime and of 
magnesia. These salts decompose the soap and combine 
with the oily acid to form an insoluble compound which 

1 " Practically it is beyond all question that, in multitudes of instances, the cess- 
pits feed the wells : and it is equally certain that such wells feed the grave-yards of 
villages and districts where this culpable neglect of hygienic precautions is allowed to 
occur." — Dr. J. G. Richardson, in " Long Life and How to Reach W 



l80 ACADEMIC PHYSIOLOGY. 

has no detergent properties. Hard water forms incrusta- 
tions in boilers and in lead pipes. In cooking, soft water 
is preferable to hard water. 

12. It has been a question whether hard water is, or is 
not, injurious to the human system. There is evidence 
that goes to prove that the presence of carbonate of lime 
in large quantities is injurious. Certain hard waters irri- 
tate the stomach and other organs of persons who are not 
accustomed to their use, and produce in such persons 
diarrhoeas. In some instances the use of hard water 
(" lime-stone water ") appears to have produced goitre 
(an enlargement of the thyroid gland of the neck), but 
this has not been positively demonstrated. Unless the 
hardness of water is very great, it may not unfit the 
water for drinking purposes ; but most physiologists agree 
in the opinion that pure, soft water is best, both for man 
and the lower animals. 

13. Action of Water upon Lead. — Injurious effects have 
frequently arisen from the contamination of water with 
lead derived from leaden pipes and cisterns. Some kinds 
of water dissolve lead quite rapidly by chemical action. 
Rain-water, and soft river and lake waters in general, 
possess the power of forming compounds with lead, which, 
if dissolved, render the water highly poisonous. All 
waters act upon it to some extent, but it is only when 
lead is dissolved that the water having it in solution 
becomes dangerous. Waters that contain vegetable acids 
(as from decaying leaves, etc.) act rapidly on lead ; while 
certain hard waters, containing sulphates and phosphates, 
have a protecting influence by means of a coating which 
they deposit upon its surface, and which is believed to 
protect lead from further chemical action. But this coat- 



NUTRITION. l8l 

ing is not always to be relied on ; and water that has 
remained for several hours in lead pipes, especially new 
ones, can never be used with assured safety. In all 
instances it is safest to allow water to run for some time, 
from leaden pipes before any is drunk or used in cooking. 

14. Means of Purifying Water. — Filtration is one of the 
most practicable and effective methods of removing im- 
purities suspended in water, but not those substances held 
in solution. Though the cleansing power of sand is not, 
strictly speaking, due to chemical action, yet there is no 
doubt that the attraction of adhesion is at work when 
water passes through it, and thus solid matters are inter- 
cepted by it. The effect of charcoal is supposed to be 
chiefly chemical. 

15. A very simple and inexpensive filter recommended 
by Dr. Parkes, is prepared as follows : " Procure a com- 
mon, earthen-ware flower-pot, and close the hole in the 
bottom with a piece of sponge, clean flannel (either of 
which requires changing from time to time), or a piece of 
zinc wire-gauze ; then put into the pot about three inches 
of gravel, and upon that the same depth of white sand, 
washed very clean. Next place in four inches of powdered 
animal charcoal, and cover it with a thin layer of coarse 
gravel, or with a piece of slate, to keep it in place." It 
is perhaps better to place a piece of thick flannel over the 
top of the pot, large enough to tie round the rim on the 
outside, and to form a hollow inside, into which the water 
is to be poured. The flannel removes the grosser impuri- 
ties floating in the water, which will flow out through the 
sponge or wire-gauze at the bottom in a greatly purified 
state. The charcoal will, from time to time, become 
clogged, and must then be renewed or cleansed by heat- 



I 82 ACADEMIC PHYSIOLOGY. 

ing in a pan over a fire. The sand and gravel should also 
be cleaned, or renewed occasionally. The principle of fil- 
tration being understood, it is quite practicable under 
almost all circumstances, to contrive some plan of pro- 
curing a sufficient supply of comparatively pure drink- 
ing-water. 

16. Distillation is a process by which ordinary well or 
mineral waters (hard waters) can be purified ; but this is 
an expensive and tedious process, and is not practicable 
when large quantities are required ; and further, distilled 
water must be aerated to render it fit for drinking pur- 
poses. 

17. Boiling expels gases, precipitates lime, and destroys 
most animal and vegetable life that water may contain. 
Temporary hardness in water may be removed by boiling. 
Many waters possess both a temporary and a permanent 
hardness, and while they are improved by boiling, are not 
rendered perfectly soft. The boiling, to be effective, 
should be continued half an hour or longer. In unhealth- 
ful districts, or during epidemics, it is a wise precaution to 
drink none but boiled water. 

18. Freezing purifies water by expelling a large portion 
of its mineral matter, such as carbonate of lime, etc. 
Distillation, boiling, or freezing of water renders it 
insipid by expelling air ; but on standing for a time, 
the water regains its palatability. 

19. Water Examined by the Senses. — The unaided senses 
are not always to be relied upon in the detection of impuri- 
ties in water. It is only in extreme conditions that im- 
purity can be detected by its taste or odor. Organic 
matter, for instance, when dissolved is often quite taste- 
less ; and water may be transparent and odorless, and yet 



NUTRITION. 183 

contain impurities that are imperceptible by the senses. 
As information obtained in this way is necessarily very 
limited and unreliable, it is best to intrust the examina- 
tion of water to a competent person whenever, from 
effects, it is suspected of being impure. 

20. Temperature of Water-Supply. — The wholesomeness of 
water depends greatly upon its temperature. The fact 
has been pointed out that any increase in the temperature 
beyond 55 renders the water unwholesome. Until the 
water delivered to a certain town reached over 6o° of con- 
stant temperature, diarrhoea did not break out in that 
town. During the following summer, the temperature of 
the water was five degrees less, and diarrhoea prevailed 
only in a slight degree. From a sanitary point, the tem- 
perature of drinking-water is extremely important. 

21. Cooling of water supplied in cities is, in summer, 
generally effected with ice. But when ice is not obtain- 
able, water in any ordinary earthen or stone pitcher, or 
other vessel, can be reduced several degrees in tempera- 
ture by evaporation, in the following way : — 

" Place several folds of linen or cotton cloth around the 
vessel, wet them as often as they become dry, and the con- 
stant evaporation will gradually abstract the heat of the 
water within the vessel. The more porous the vessel is, 
the more rapidly will the water cool." 



184 ACADEMIC PHYSIOLOGY. 

CHAPTER XX. 

drinks {continued). — narcotics and stimulants. 

1. Artificial Drinks. — All drinks may be divided into two 
classes ; viz., natural drinks and artificial drinks. To the 
first of these belong water and milk ; and to the second, 
tea, coffee, cocoa, and the various alcoliolic beverages. The 
artificial drinks are employed, in general, for nervous 
stimulation rather than for any nutritive properties of 
their own, and not because they relieve thirst more effect- 
ually than the natural drinks. While some artificial 
drinks may be useful when taken with care, yet they are 
extremely liable to prove very injurious to health when 
too freely used. 

2. Tea. — On being analyzed, tea is found to contain 
(1) a volatile, essential oil which gives tea its agreeable 
aroma; (2) a vegetable alkali, called tJieiue, which is nitro- 
genous and is the active or stimulating principle of tea ; 
(3) ta7tnic acid, which produces an astringent effect upon 
the bowels, but not usually to a harmful extent ; and (4) 
gluten, salts, etc., which are not commonly obtained in 
the beverage. The varieties known as green teas and 
black teas differ only in the mode of drying the leaf. In 
China, tea is seldom used till it is a year old because of 
the well-known intoxicating properties of new tea. " Tea- 
tasters," engaged regularly in testing the quality of tea 
by its aroma and flavor, frequently complain of head-ache 
and giddiness ; and persons engaged in packing teas for a 
few years are liable to attacks of paralysis, it is said. 



NUTRITION. 185 

3. Some authorities have over-praised the dietetic and 
medicinal values of tea, while others have declared it to 
be the source of diseases, especially of the nervous sys- 
tem. When the decoction is not too strong, it usually acts 
as a gentle stimulant upon the nervous system, and invig- 
orates without producing subsequent weakness or depres- 
sion. If it is taken in excess, it is apt to cause nervous 
wakefulness and indigestion. As a rule, tea is injurious 
to young persons, and is not a suitable drink till youth 
is completed. Adults of an irritable, nervous tempera- 
ment often suffer from its use. " Old and infirm persons 
usually derive more benefit and satisfaction from it than 
from any other corresponding beverage." Tea proves a 
useful sedative in certain forms of heart disease, while in 
others it acts injuriously. The persistent use of strong 
tea for the purpose of keeping awake (a practice adopted 
by some students and by other persons) is certain to 
result in a loss of both bodily and mental vigor. 

4. Coffee. — Coffee, like tea, contains a volatile oil which 
gives it a peculiarly agreeable aroma; a vegetable alkali 
(caffeiii) almost identical in composition with theine of 
tea, to which it owes its exhilarating power ; and tannic 
acid, though in smaller quantity than tea. It also con- 
tains sugar, gum, and salts ; but these latter substances 
do not enter largely into the beverage. The effects of 
coffee are similar to those of tea, and what has been 
remarked of tea applies to coffee as well. 

5. Tea and coffee, although they are not positive foods, 
appear to retard the waste of tissue ; and if the waste be 
lessened, the necessity for food to repair that waste will 
be diminished proportionately. If, however, they are 
relied on to supply by their stimulus the place of positive 



1 86 ACADEMIC PHYSIOLOGY. 

food, they produce nervousness and dyspepsia. In a 
description of experiences during Arctic exploration, Dr. 
Hayes makes the following statement : " The men seemed 
to grow hungry less rapidly after taking coffee than after 
drinking tea, while the tea soothed them after. a day's 
hard labor, and the better enabled them to sleep. They 
both operated upon fatigued and over-taxed men like a 
charm, and their superiority over alcoholic stimulants was 
very marked." 

6. Cocoa. — Cocoa or chocolate is prepared from the 
ground seeds of the fruit of the cocoa palm. It contains 
a substance (theo-bromine) very similar to, but not identi- 
cal with, theine or caffein. Cocoa contains also from 
45 to 49 per cent of fat, and from 14 to 18 per cent of 
nitrogenous matter (albumen, starch, and sugar). While 
not so stimulating as tea or coffee, it will be understood 
from its composition that cocoa may be classed among the 
most nutritious foods. But few foods appease hunger 
better, or give greater nourishment, than a beverage pre- 
pared from cocoa and milk ; and an eminent physiolo- 
gist says, " It is equally good for all ages, classes, and 
circumstances." 

7. Adulterations of Tea, Coffee, and Cocoa. — Tea of all varie- 
ties is often adulterated in one or more of the following 
ways: (1) Inferior varieties are mixed with the better 
kinds ; (2) Exhausted leaves (grounds) are dried and 
mixed with fresh leaves ; (3) the leaves of other plants 
(particularly those of the willow, elder, and beech) are 
mixed with the tea leaves ; (4) green tea is sometimes 
tinted with indigo, Prussian blue, turmeric, or gypsum ; 
and a bright-green tea should be suspected of adultera- 
tion, as the pure article is of a dull-green color ; and 



NUTRITION. 187 

(5) black tea is sometimes tinted with graphite (black 
lead). 

8. Coffee, when unground, cannot be adulterated easily ; 
but ground coffee in packages is almost always adulter- 
ated — often, in fact, is not coffee at all. Package "cof- 
fees " usually consist of a very small quantity of the 
genuine article adulterated with chicory, pease, wheat, 
acorns, and corn. As these latter grains cost much less, 
the temptation to mix them with coffee is very great. 

9. Chocolate and cocoa are often adulterated by the 
addition of too much sugar, or with starch, cinnamon, etc. 

10. Alcoholic Beverages. — Alcoholic beverages include all 
those liquids that owe their stimulating and later narcot- 
izing effects to the alcohol they contain. In speaking of 
the use of alcohol as a beverage, we do not mean that it 
is used in a pure state at any time. 

11. Alcohol is the product of the decomposition of some 
form of saccharine matter, by means of fermentation. 
Both sugar and starch are vegetable products, and the 
latter is readily modified in composition so that sugar is 
produced from it. Sugar and starch may therefore be 
regarded together as the source of alcohol. Various 
fruits, grains, and tubers, such as the apple, grape, corn, 
rye, potato, and beet, yield sugar and starch abundantly. 

12. Ferment atio?i is the chemical process by which sugar, 
when subjected to the proper degree of temperature, is 
decomposed, and alcohol and carbonic acid gas are pro- 
duced. Thus, the juice of apples kept at a temperature 
of yo° Fahr. undergoes a change in which bubbles of gas 
arise to the surface, the sugar of the juice is changed to 
alcohol, and a marked difference in the odor and the taste 
of the juice ensues, 



I 88 ACADEMIC PHYSIOLOGY. 

13. When grain is moistened and kept in a warm place, 
it begins to grow ; and when chewed is found to taste 
sweet, part of the starch having been changed to sugar. 
By adding warm water and yeast to the grains, the sugar 
thus formed will ferment and produce alcohol and carbonic 
acid gas, as in the fermentation of apple juice. 

14. The Fermented Liquors in common use as beverages 
are cider, wine, and beer: — 

Cider is fermented apple juice, and contains from i to 
15 per cent alcohol. 

Wines are principally derived from the fermented juice 
of grapes, although other fruits are sometimes used in the 
manufacture of domestic or " home-made " wines. All 
wines contain alcohol, sugar, vegetable acids, and some of 
them contain tannin derived from the skin of the grape. 
The quantity of alcohol varies from 5 to 25 per cent in 
the different kinds of wine. Stimulating beverages called 
wines have been known by all nations and in all periods 
of the world's history, and have been used and allowed to 
abuse from the earliest times of which we have any record 
down to the present day. 

Beer is made from fermented infusions of grains or 
malt, flavored with hops. The amount of alcohol con- 
tained in the various kinds of beer and ale varies from 3 
to 10 per cent. 

15. The Distilled Liquors in common use as beverages are 
brandy, wJdskey, gin, and rum. These are produced by 
distilling fermented liquors, the alcohol they contain 
having been formed during the process of fermentation. 
Distillation consists in the separation of any two liquids 
that boil at different degrees of temperature. As alcohol 
boils at 1 73 F., and water at 21 2° F., if a mixture of 



NUTRITION. 189 

the two be kept at a temperature above the boiling point 
of the former and below that of the latter, the alcohol will 
pass off in volatile form, accompanied by some vapor of 
the water. The vapory products thus driven off by heat 
are condensed, by conducting them through coils of cold 
pipes. The liquid thus obtained contains all the alcohol, 
a part of the water, and the volatile oils of the fermented 
liquors, and hence is much stronger than the latter. By 
repeated distillations, alcohol that is almost absolutely 
pure is obtained : — 

Brandy is produced by distilling wine. It is colorless 
at first, but soon acquires an amber tint from the tannic 
acid of the casks. All dark brandy is artificially colored. 
New brandy contains from 50 to 60 per cent of alcohol. 

Whiskey is usually made by distilling malted barley, 
though rye and other grains are also employed. It con- 
tains from 50 to 60 per cent of alcohol. 

Gin is obtained by distillation of unmalted grains, and 
is flavored with juniper berries. It ordinarily contains 
somewhat less alcohol than brandy or whiskey does. 

Rum is the product of the distillation of fermented 
molasses and skimmings of sugar boilers. It contains 
alcohol to the amount of 60 to 70 per cent. 

16. The wines contain some free sugar, essential oils, 
and coloring matter from the fruits. Beer holds in solu- 
tion sugar, dextrine, certain bitter essences, carbonic acid, 
etc. Brandy, whiskey, gin, and rum contain more or less 
sugar and certain volatile oils derived from the grains. It 
is the alcohol, however, in all these liquors that gives them 
their peculiar, stimulating, intoxicating, or noxious effects 
when used as beverages. If the alcohol they contain 
were removed, the remaining constituents would not ren- 



I9O ACADEMIC PHYSIOLOGY. 

der these liquors especially attractive. Many other arti- 
ficial beverages are much more agreeable to the taste 
and produce greater tonic effects than the alcoholic 
liquors. 

17. Adulteration of alcoholic beverages is very com- 
mon, and so extensive as to make purity the exception. 
"While adulteration of alcoholic beverages is so exten- 
sive, the subject is more alarming from the character of 
the substances so shamefully employed, and from their 
effects upon the human system. However questionable 
the effects of alcohol itself, there can be no doubts as to 
the evil consequences to follow from the violent poisons 
employed in its adulteration." Certain publications de- 
voted to the interests of manufacturers of and dealers in 
alcoholic liquors, give specific directions for modifying 
wines, beers, and distilled liquors, giving them color, 
flavor, etc., by the use of such substances as opium, aloes, 
nux vomica, tobacco, arsenic, strychnia, sugar of lead, 
white lead, red lead, logwood, copperas, and alum. 

18. Alcohol and its Properties. — Alcohol, produced by the 
processes of fermentation already described, is a colorless 
liquid having an agreeable odor and a hot, pungent taste. 
It is lighter than water, very volatile, and highly inflam- 
mable. When ignited, its burning is accompanied by a 
very hot, blueish, smokeless flame. It possesses pecu- 
liarly important solvent powers, and readily dissolves 
gums, resins, and oils ; it is therefore a highly useful 
agent in extracting these substances from leaves, seeds, 
barks, and roots. Many alcoholic tinctures containing 
the essential oils, or other medicinal elements of vegeta- 
ble substances, are thus formed. It is largely used in the 
arts and sciences for similar purposes. As alcohol does 



NUTRITION. . 191 

not freeze, it is employed in spirit-levels, and in ther- 
mometers for very low temperatures. 

19. One of the most remarkable properties of alcohol is 
its affinity for water, the two uniting and being held in 
solution in each other in any proportion. It greedily 
absorbs water from organic substances, and preserves 
animal matter immersed in it from decomposition. Its 
antiseptic properties are equalled only by those of arsenic, 
creosote, and carbolic acid. 

20. Like other narcotics, alcohol tends to allay pain 
when taken into the system, and this it does by deaden- 
ing the sensibility of the brain and nerves, to which it is 
carried by the blood in its circulation. But as powerful 
as its proper use may be for good, the terrible results that 
follow its abuse, when it is used as a beverage, have caused 
many physicians to seriously question the advisability of 
prescribing it, the liability to become addicted to habitual 
alcoholic drinking being very great. 

21. Alcohol as a Beverage and as a Poison. — A true bever- 
age supplies the large amount of water needed by the 
tissues, without introducing any noxious element with it, 
and allays thirst. Substances which have great affinity 
for water extract it from the tissues when introduced into 
the body, tending thereby to cause shrinkage, hardening, 
and stiffening of such parts as are in contact with them. 
By absorbing water from the tissues they create thirst. 

Dilute alcohol, as in the various alcoholic drinks, acts in 
this manner. In its strongest form, alcohol taken into the 
mouth or stomach will blister the mucous membrane and 
disorganize the structure of other tissues, so great is its 
affinity for the water contained in them. 

In a similar way, only in less degree, any form of dilute 



192 ACADEMIC PHYSIOLOGY. 

alcohol inflames tissues and produces thirst, while a true 
beverage always tends to allay thirst. It is true that the 
large amount of water in beer enables it to slake thirst ; 
but it is also true that the water of the beer would assuage 
thirst more readily in the absence of the alcohol. 

22. It is the function of the blood, so largely composed 
of water, to hold the food particles in solution. Alcohol, 
other than in very small quantities, arrests the digestion 
of food by hardening the albuminous particles and render- 
ing them incapable of solution. In this action it is again 
the reverse of a true beverage. 

23. Acting as a poison in dram-drinking, alcohol par- 
alyzes the nerve centres, causes disease of the kidneys and 
liver, destroys digestion, deteriorates the blood, and invari- 
ably leads to chronic alcoholism and premature death. 

24. When a considerable quantity of alcohol is taken 
during or after a meal, instead of aiding digestion it sepa- 
rates the pepsin from the gastric juice, and thus completely 
arrests digestion and causes immediate distress. If this is 
continued for a short time the function of the stomach is 
seriously interfered with. When it is taken before the 
day's labor begins, it does absolute harm. " Both body 
and mind will be incapacitated, the life shortened, and all 
the keenest joys taken out of what remains." 

25. Of the moral effects of the abuse of alcohol, and of 
its special action on various organs and their functions, we 
have written in other chapters. That it inflicts untold 
misery upon thousands besides its immediate victims, no 
one will deny. 



DIGESTION. I93 



CHAPTER XXI. 

DIGESTION. MASTICATION, INSALIVATION, AND DEGLU- 
TITION. 

1. Digestion. — Digestion is a complex process, and is 
one of the chief of the organic functions concerned in the 
maintenance of life. It is that process, or, rather, series 
of processes, by which food is modified, or undergoes vari- 
ous changes which prepare it for appropriation by the 
tissues and structures of the body ; or, in other words, 
for conversion into blood. Perfect digestion and nutri- 
tion imply assimilation of nutrient material to the bodily 
structures without excitement or disturbance of any kind. 
There can be nothing of greater importance to physical 
well-being, and hence to the attainment of long life, than 
good appetite and good digestion, the two evidences of 
a healthy digestive apparatus. The immortal dramatist 
causes Macbeth to say : — 

" Let good digestion wait on appetite, 
And health on both." 

2. In the words of Dr. J. G. Richardson, " If we con- 
sider the amount of ill-temper, despondency, and general 
unhappiness which arise from want of proper digestion 
and assimilation of our food, it seems obviously well worth 
while to put forth every effort, and undergo any sacrifice, 
for the purpose of avoiding indigestion, with its resulting 
bodily ills ; and yet, year after year, from the cradle to the 



194 ACADEMIC PHYSIOLOGY. 

grave, we all go on violating the plainest and simplest laws 
of health, at the temptation of cooks, caterers, and confec- 
tioners, whose share in shortening the average term of life 
is probably nearly equal to that of the combined armies 
and navies of the world." 1 

3. Organs and Processes of Digestion. — The digestive appa- 
ratus is one of the most complex and extensive in the 
body. The organs of digestion are : — 

1. The mouth, and its appendages — the teeth, tongue ; 
salivary glands, etc. 

2. The pharynx. 

3. The ossophagus. 

4. The stomach, liver, and pancreas. 

5. The intestines. 

6. The absorbents, — lac tea Is, etc. 

The spleen and kidneys are appendages of the digestive 
apparatus, but belong rather to the circulatory or excretory 
system. The organs of digestion are situated mainly in 
the abdomen. 

4. Beginning at the mouth, these organs, together with 
the passages that connect them, form a long, muscular, 
membranous tube, called the alimentary canal, which in 
adults is from twenty-five to thirty feet in length, and 
extends throughout the trunk. It is lined throughout 
with firm, delicate tissue, similar to that of the internal 
cavities in general, and known as the mucous membrane. 
Besides the digestive juices which it secretes, it sends out 
a glutinous fluid, called mucus, which moistens and pro- 
tects the delicate lining, and enables its opposing surfaces 
to glide smoothly upon each other when brought in con- 
tact by the movements of digestion. The middle coat of 

1 " Long Life and How to Reach It," in American Health Manual. 



DIGESTION. 



195 



the canal consists of two sets of muscular fibres, one 
of which surrounds the tube like a series of rings, while 
the other extends longitudinally, or in the same direction 
as the tube itself, be it oesophagus, stomach, or intestine. 




Fig. 39. 



This figure represents the organs of the chest and abdomen in natural position, the 
breast-bone and ribs being removed. 



EXPLANATION. 



B, the trachea or (windpipe). 

C, cesopJiagus or (gullet). 

E, diaphragm. 

F, liver. 
I, spleen. 



D, stomach. 

G, intestines. 

H, heart, the pericardium being laid open. 

A, lungs. 

J, bladder. 



The outer coat is smooth and soft. The various portions 
of the canal differ in form, size, and general structure. 



I96 ACADEMIC PHYSIOLOGY. 

5. Finally the stomach and other organs situated in 
the abdomen are invested by a sac-like membrane, the 
peritoneum (Gr. peri, around ; teinein> to stretch), which 
attaches them to the vertebral column and, to the walls of 
the abdomen upon which it folds back and which it lines. 
That part of the fold behind the intestines fastens itself 
to the front of the vertebral column, and is called the 
mesentery (mesos, middle ; enteron, intestine). 

6. The processes of digestion may be classed as fol- 
lows : — 

1. Mastication, 

2. Insalivation, 

3. Deglutition, or swallowing, 

4. Chymification, or stomach digestion, 

5. Chylification, or intestinal digestion, 

6. Absorption of the chyle. 

7. All of these processes are important, and each of 
them must be properly conducted in order to maintain a 
healthy condition of the body. If any one of them is 
carried on imperfectly, the others, so intimately related 
and dependent, will be affected. We now proceed to a 
consideration of the various acts of which the digestive 
function is made up. 

8. Mastication. — The operation of mastication, performed 
by the teeth and aided by the action of the tongue, cheeks, 
etc., is of the highest importance, since the more the 
food is broken down the more easily will the saliva and 
other digestive fluids mix with it in the digestive pro- 
cesses. The cavity of the mouth is bounded by the 
palate or roof of the mouth, and in other directions by 
the cheeks, lips, and tongue. Projecting into the cavity 



DIGESTION. 197 

above and below are the teeth of the upper and the lower 
jaw. The upper jaw (and consequently the dental arch 
which forms a part of it) is immovable, or can be moved 
only with the entire head. The lower with its teeth is 
capable of movement, by means of the powerful muscles 
of mastication, in five directions, viz., upwards, down- 
wards, backwards, forwards, and laterally. By the varied 
movement of the lower jaw, the lower teeth grind the 
food against the upper, while the tongue and cheeks roll 
it about and keep it in place ; and thus the food is broken 
down or masticated. 

9. The forms of the various classes of teeth fit them for 
the several processes of dividing the food. The front in- 
cisors, or cutting-teeth, are sharp on the edges for the pur- 
pose of dividing the food into smaller portions ; the cuspids, 
or eye-teeth, which project a little beyond the others, 
grasp the food more firmly ; the bicuspids, next in order, 
and having two prominences on their points, break the 
food into finer particles ; and lastly, the molars, or grind- 
ers, reduce and crush the food into a pulpy mass. 

10. Mastication is the only digestive process that is 
entirely or directly under the control of the will ; and 
hence, an individual can " do more toward preventing 
dyspepsia and other disorders of the digestive apparatus 
by giving proper attention to the mastication of his food 
than in almost any other way." A glance at the anatom- 
ical structure of the teeth should alone be sufficient to 
impress the observer with the importance of " eating 
slowly and chewing deliberately." 

11. In commenting upon a curious controversy as to 
the need or value of " biting one's food," the Lancet says : 
" Strange as it must appear, there are some, who should 



I98 ACADEMIC PHYSIOLOGY. 

be authorities, ready to affirm that it is futile to take the 
trouble to use the teeth with which nature has provided 
man, in common with other animals, apparently for the 
purpose of cutting and grinding his food. . . . Mean- 
while, we counsel all who care for their comfort, and 
who do not desire to develop the worst form of dys- 
pepsia, to continue the practice of mastication as be- 
fore. As a matter of fact and experience, a liberal use 
of the teeth in feeding is one of the essentials in easy 
digestion ; . . . first, to divide the food and crush its 
fibres and particles generally ; and secondly, to mix it so 
thoroughly with the secretion from the salivary glands 
that not only shall the act of deglutition be rendered 
easy, but that the food when it enters the stomach shall 
have been properly prepared for digestion in the gastric 
juice." 

12. It is certain that, since the stomach has no teeth, 
it was not designed to masticate food ; and it is obvious 
that the preservation of the natural teeth is one of the 
most important considerations in the personal care of the 
health. 

13. Insalivation. — No part of the digestive process is 
more important than the insalivation and thorough masti- 
cation of food in the mouth ; and yet, by many # people, 
these processes are seldom regarded or appreciated. All 
realize the necessity of moistening dry food when it is re- 
ceived into the mouth ; and if this were the only office to 
be performed by the fluid secretions of the mouth, the 
substitution of tea, coffee, water, and other liquids instead, 
for the purpose of moistening food, might be admissible. 
There are, however, other results to be produced ; and 
hence it is highly important that food be mixed with, 



DIGESTION. 199 

moistened by, and subjected to the chemical action of 
fluids which nature prepares within the walls of the cavity 
of the mouth. This natural moistening and mixing is 
termed iusalivation. 

14. The Salivary Glands and their Action. — Besides the nu- 
merous minute buccal glands which beset the mucous lin- 
ing of the mouth, there are six distinct glands, three on 
each side of the cavity of the mouth, from which it receives 
its chief secretions. These pairs, called salivary glands, 
are composed of masses of tiny sacs, blood-vessels, and 
tubes held together by connective tissue, and are named, 
respectively, the parotid, the submaxillary -, and the sublin- 
gual glands. 

15. Each parotid gland is situated behind one of the 
angles of the lower jaw and forward of the ear. The duct 
through which it sends its secretion into the mouth passes 
forward along the cheek, and opens in its interior surface, 
opposite the second upper molar tooth. The parotid 
glands are the largest of the salivary glands. 

16. The submaxillary glands are located just within the 
angles of the lower jaw, and their ducts open under the 
tongue, at its junction with the floor of the mouth. 

17. The sublingual glands, which are the smallest of the 
salivary glands, are located under the tongue, beneath the 
membrane of the floor of the mouth, and their ducts open 
near the openings of the submaxillary glands. It is the 
office of all these glands to separate, or secrete, a fluid 
from the blood ; and their secretions, mingled with that 
of the small glands of the mucous surface of the mouth, 
constitute the saliva. 

18. The presence of food in the mouth, or, often, the 
mere thought of food, excites the salivary glands to action ; 



200 ACADEMIC PHYSIOLOGY. 

and the act of .mastication further induces the flow of 
saliva. Hence, unless some portion of our food is of a 
solid consistence, and therefore requires thorough masti- 
cation, it does not become properly mixed with the saliva. 

19. Nature and Action of Saliva. — The saliva is a colorless, 
turbid fluid, and, though thin and watery, it contains small 
quantities of animal matter which have very peculiar prop- 
erties. Its reaction is alkaline, and the degree of alkalin- 
ity varies, being greater during and after meals. The 
daily average amount of saliva secreted by the glands of 
an adult man is estimated to be about three pounds or 
pints. 

20. The action or use of saliva in the digestion of food 
is partly mechanical and partly chemical. Mechanically, 
it moistens dry food, and thus serves the double purpose 
of preparing it to be swallowed and of separating its par- 
ticles so that they may be more freely acted upon by other 
digestive juices in the stomach and intestines. Besides 
moistening, it lubricates each bolus of food, and thus facil- 
itates its deglutition. Chemically, the saliva acts upon 
the amylaceous or starchy portion of the food, and turns 
the starch into grape-sugar. 1 The great importance of 
this action of the saliva will be comprehended when it is 
understood that starch is insoluble as nutriment, and can- 
not be appropriated by the tissues and structures ; while 
sugar is easily soluble and assimilable. Thus it will be 
seen that while water, milk, tea, coffee, and other liquids 
may be used to moisten food, none of them can be substi- 
tuted for saliva without impairing digestion, as none of 

1 This chemical change is produced by the ptyaline of the saliva, an ingredient 
which acts as a ferment ; that is to say, under favorable conditions of moisture and 
heat, " it changes the chemical constitution of a substance for which it has an affinity." 



DIGESTION. 20I 

them have the property of changing starch into sugar. 
Saliva does not act upon proteid substances, nor upon the 
oils or fats of food-stuffs. 

21. Tobacco and Salivary Digestion. — Chewing and smok- 
ing of tobacco exhaust the salivary glands of their secre- 
tion, thus producing dryness and thirst ; or the saliva, 
being tainted with tobacco, is rendered unfit for its office 
and is wasted. The starchy portions of the food which 
should be acted upon by the saliva remain partially un- 
changed. Those addicted to the excessive use of tobacco 
often have " a morbid running or drivelling from the 
mouth, not of true saliva, however, but of a depraved and 
acrid secretion (caused by over excitement and irritation 
of the glands), analogous to that of catarrh of the head 
and other morbid affections of the mucous membrane." 
In this latter instance, the salivary glands become sewers, 
as it were, for the excretion of waste matter from the 
blood, and excessive thirst is produced. 

22. Action of Acids on Salivary Digestion. — The influence 
of acids in retarding or arresting salivary digestion is of 
importance in the use of pickles, vinegar, acid fruits, etc. 
In the case of vinegar it has been found that I part in 
5,000 sensibly retarded the process of converting starch 
into sugar, 1 part in 1,000 rendered it very slow, and 1 
part in 500 arrested it completely. When, therefore, 
acid salads are eaten with bread, the effect of the vinegar 
is to prevent the salivary digestion of the starch of the 
bread ; this, to a person of vigorous digestion, may be a 
matter of little moment ; but to a feeble dyspeptic, one of 
some importance. The belief that drinking of vinegar is 
an effective means of avoiding or reducing corpulence 
appears to be well founded, especially if the vinegar be 



202 ACADEMIC PHYSIOLOGY. 

taken at the same time as starchy food, as it will greatly 
interfere with its digestion and assimilation. 

23. Deglutition. — Deglutition, or swallowing, is the act 
by which the food is transferred from the mouth to the 
stomach. After mastication and insalivation are com- 
pleted, the tongue moves the mass backward into the 
pharynx, the funnel-shaped cavity which is located behind 
the mouth and at the first bend of the alimentary canal 
downward. Between the mouth and the pharynx is the soft 
palate, which is a movable muscular partition that separates 
the two cavities during mastication. As soon, however, as 
the food is moved backward by the tongue, the soft palate 
is drawn obliquely upwards and backward so as to close 
completely the passage between the pharynx and the nose, 
thus performing the part of a double valve, and permitting 
the food to enter the pharynx. (When the pendulous soft 
palate is destroyed by disease, both the swallowing of food 
and the tones of the voice are rendered more or less im- 
perfect). Having arrived at the oesopJiagns, or gullet (the 
next portion of the canal, and continuous with the pharynx), 
the bolus of food is driven into it by the action of certain 
muscles called constrictors, which form the walls of the 
pharynx. 

24. Whenever the act of swallowing is performed, the 
opening in the wind-pipe is closed by a valve (the epiglottis), 
and that into the nose by the soft palate, so that during 
this operation all ingress of air to the lungs is prevented ; 
and consequently, it is necessary that the passage of food 
through the pharynx should be rapid. " All voluntary 
action ceases as soon as the food is passed into the pharynx, 
and it is necessarily carried on into the stomach, in spite 
of our will." Life depends upon the passage of the food 



DIGESTION. 203 

through the pharynx with extreme rapidity and the nicest 
precision. 

25. The oesophagus, which connects the pharynx with 
the stomach, is about nine inches in length, and is located 
in front of the upper portion of the spinal column, and 
behind the wind-pipe. Like other portions of the aliment- 
ary canal, its muscles are of the involuntary kind, some of 
them surrounding it in a circle, while others run length- 
wise. When these two sets of muscles contract together, 
they force forward the food within their grasp, and it is 
thus driven into the stomach. The act of deglutition is 
then complete. 



CHAPTER XXII. 

CHYMIFICATION, OR STOMACH DIGESTION. 

1. The Stomach. — The stomach is a muscular bag, of an 
irregular oval shape, which is often compared to that of the 
air-bag of a bag-pipe. It is located transversely across the 
upper part of the abdomen ; and while it varies in size in 
different persons, in the average adult it is capable of con- 
taining about three fluid pints. 

2. The oesophagus opens obliquely into the left extremity 
of the stomach by an aperture called the cardiac orifice, 
so named because of its nearness to the heart. This 
orifice is guarded by a muscle surrounding it in a circular 
form, and which can contract so tightly as to prevent the 
passage backward of substances that have entered the 
stomach. At the right extremity, the stomach opens into 



204 



ACADEMIC PHYSIOLOGY. 



the duodenum by a small aperture, called the pyloric 
orifice, which is surrounded by a strong, circular muscle 
presenting the appearance of a prominent band, and called 




Fig. 40. The Organs of Digestion. 
EXPLANATION. 



a, the oesophagus, 
i. the pancreas. 

c, the stomach. 

d, the spleen. 

e, the small intestine. 



/, the large intestine, 
h, the appendix, 
j, the gall-bladder, 
k, the liver. 
I, the pylorus. 



the pylorus (Gr. puloros, a gate-keeper). The office of 
the pylorus is to guard the opening and prevent the exit 
of aliment while it is being digested in the stomach, 



DIGESTION. 205 

Between the two orifices are the two curvatures of the 
stomach, the upper one, called the smaller, and the lower 
one the greater curvature. 

3. The inner or mucous* coat of the stomach is thick and 
soft, and lies in irregular folds, termed rugce, whose object 
is to enlarge the space for blood-vessels, nerves, etc. The 
rest of the thickness of this coat is chiefly made up of 
minute tubes running to the inner surface of the stomach ; 
these are the gastric tubes, or glands, which secrete the 
gastric juice from the blood in the capillaries of the 
mucous lining. 

4. The middle, or muscular coat consists of longitudinal 
muscular fibres and of circular ones. The contraction of 
these fibres diminishes the length and the diameter of the 
stomach ; and hence, the food, acted upon by both sets of 
muscular fibres, is turned and compressed in various ways 
during digestion. 

5. The outer or peritoneal coat is formed of a membrane 
already mentioned, the peritoneum, which, while retain- 
ing the stomach and intestines in place, permits their 
necessary movements. 

6. The Gastric Juice. — The changes which the food un- 
dergoes in the stomach are due to the action of the gas- 
tric juice, the acid fluid which Dr. Beaumont saw exuding 
from the mucous membrane of the stomach of St. Martin. 1 

1 In 1822 a Canadian named Alexis St. Martin, employed by a fur-trading com- 
pany, received a severe wound in the left side, by the accidental discharge of a gun. 
He was attended by Dr. Beaumont, and his health was finally completely restored, 
though, strange to say, there was left an opening into the stomach, about four-fifths 
of an inch in diameter, closed by a flap of membrane which could be pushed inward. 
Dr. Beaumont kept St. Martin in his employment for several years, made hundreds 
of observations upon him, noticed the effects of various kinds of food, and ascertained 
the time required to change it into chyme. " Dr. Beaumont was the first, and for 
many years the only, person who ever saw the interior of the stomach in a living 



206 



ACADEMIC PHYSIOLOGY. 



This fluid is colorless, slightly viscid, and invariably acid. 
Its two important or essential elements are hydrochloric 



A 




Fig. 41. The Stomach laid open in front. 
EXPLANATION. 

a, the oesophagus or gullet ; b, the pylorus ; c, the bile duct extending from the liver; d, the 
gallbladder; e, the duodenum ; /, the pancreatic duct; g, the small, intestine ; S, the 
stomach, showing the folds (or ntgce) of the inner coat or mucous membrane. 



or lactic acid, and anorganic ingredient which, on analysis, 
is found to be highly nitrogenous, and which is called 
pepsin. If the juice be deprived of these constituents, 

man ; and to his observations we owe much of our knowledge of stomach digestion. 
Experiments upon animals have also aided greatly in determining the laws of 
digestion," 



DIGESTION. 207 

it becomes incapable of performing its office in the diges- 
tion of food. 

7. The gastric juice serves to dissolve and to transform 
the nitrogenous matters of food, such as albumen, fibrin, 
casein (lean meat, the white of eggs, the gluten of wheat, 
etc.), converting them into substances, termed peptones, 
which are in condition to be absorbed and to enter the 
blood. The gastric juice also releases fat from its enve- 
lopes, by breaking them up ; but the best authorities agree 
that the gastric juice exerts no great influence upon the 
fat, sugar, or starch of food. It is supposed that saliva 
flows down into the stomach and acts upon starchy food 
that may have escaped action in the mouth. 

8. The quantity of gastric juice secreted daily by an 
adult person averages about fourteen pounds ; that is, 
about a gallon and a half. Dr. Beaumont remarks in his 
little book: " The gastric juice never appears to be 
accumulated in the cavity of the stomach while fasting. 
When aliment is received, the juice is given out in exact 
proportion to its requirements for solution, except when 
more food has been taken than is necessary for the wants of 
the system." 

9. Stomach or Gastric Digestion. — The stomach during 
chymification is a closed chamber ; its cardiac orifice is 
closed by the valved entrance of the oesophagus, and its 
pyloric orifice by the contraction of the pylorus. The 
muscular coat contracts in a slow, regular manner, rolling 
and otherwise moving the contents of the stomach in a 
peculiar way, and thus mixing the food with the gastric 
juice. 

10. The arrangement of the food in the stomach has 
been described as follows : " The food first received is 



208 ACADEMIC PHYSIOLOGY. 

placed outermost, that is, nearest the inner surface of 
the stomach ; the portion next taken is placed interior to 
the first, and so on in succession, until the food last taken 
occupies the centre of the mass. Soon after the food has 
been thus arranged, a remarkable change takes place in 
the mucous membrane of the stomach ; the blood-vessels 
become loaded with blood, and the minute cells between 
the rugae overflow with fluid, the gastric juice." Dr. 
Beaumont, who saw what he describes, says that the 
course and directions of the food on entering the stomach 
are first, from right to left and downward along the 
greater curvature towards the right, or pyloric extremity ; 
it then moves along the smaller curvature, or upper sur- 
face of the organ, to its left extremity, each circuit re- 
quiring from one to three minutes. 

11. In the food itself no change is manifest for some 
time ; but at length, that portion of it which is in imme- 
diate contact with the mucous surface begins to be 
slightly softened. This softening slowly increases, and 
ultimately the most solid portions of the food are com- 
pletely dissolved. The dissolved and detached portions 
flow toward the pyloric extremity of the stomach. The 
fluid which thus accumulates, slowly but steadily, is a new 
product in which the sensible properties of the food, no 
matter what the variety of its substances, are lost ; all 
have been resolved into an homogeneous, grayish, slightly- 
acid fluid, called chyme. 

12. As soon as the chyme, by its gradual accumulation 
in the pyloric extremity, amounts to about two or three 
ounces, the pylorus relaxes, opens, and permits the fluid 
to be squeezed or pressed through the opening into the 
duodenum, or first section of the smaller intestine. When 



DIGESTION. 209 

the duly prepared portion of the chyme has passed out of 
the stomach, the pylorus closes, and remains closed until 
another like quantity has accumulated, and then repeats 
its former action, renewing it again as long as this process 
of chymification continues. 

13. The ordinary temperature of the interior of the stom- 
ach is ioo° F. Cold liquids taken with food tend to lower 
the temperature, and hence to retard stomach digestion. 

14. Absorption from the Stomach. — But do all the sub- 
stances that are thoroughly dissolved in the stomach pass 
out of the stomach through the pyloric valve ? As already 
intimated, a portion of the products of stomach digestion 
(consisting of peptone mixed with saliva and saccharine 
fluids) are at once absorbed through the walls of the num- 
erous and delicate blood-vessels (capillaries) of the stom- 
ach, and pass out into the blood. " As the veins of the 
stomach, which are formed by the union of these capil- 
laries, contribute to form the portal vein> the absorbed 
matters pass directly to the liver, and probably stimulate 
it to increased secretion," etc. 

15. Time required for Stomach Digestion. — The rapidity 
with which the chymification of food is carried on varies 
according to the digestibility of the food, the size of the 
morsels swallowed, the quantity received by the stomach, 
and the state of the health of the individual. In about 
five hours after an ordinary meal, all of the food taken is 
probably converted into chyme. 

16. The foods which are soonest dissolved in the 
stomach are not necessarily the most nutritious ; and it 
matters not whether a given aliment digests in two hours 
or in four, so far as its nutritive value is concerned. But 
those articles which require a long time for solution tax 



210 



ACADEMIC PHYSIOLOGY. 



the powers of the stomach severely, and, if it is not vigor- 
ous, such articles often prove absolutely indigestible. 
Speaking of delayed digestion, Huxley remarks : "If ali- 
ment is not absorbed into the system from the digestive 
apparatus, it rapidly undergoes chemical decomposition in 
the alimentary canal, and often putrefies." 

Table giving the Length of Time required for the Digestion of a Few of the most Ordi- 
nary Kinds of Food. 



Articles. 



Pork, fat and lean 
Suet, beef, fresh . . 
Cabbage, with vinegar 
Ducks, domestic . . 
Ducks, wild .... 
Cheese, old, strong . 
Eggs, fresh .... 
Eggs, fresh .... 
Chicken, full grown . 
Bread, white . . . 
Potatoes, Irish . . . 
Codfish, dry .... 
Soup, bean .... 
Soup, barley .... 

Rice 

Oysters, fresh . . . 
Apples, sweet . . . 
Dumpling, apple . . 

Beef 

Beefsteak 

Veal 

Sausages 

Milk 

Milk 

Custards 

Soup, beef, vegetables 



Time. 



Condition. 












Hours. 


Minutes. 


Roasted . . . 


5 


i.5 


Boiled . 








5 


3° 


Boiled . 








4 


30 


Roasted . 








4 


00 


Roasted . 








4 


3° 


Raw . . 








3 


30 


Boiled hare 








3 


30 


Raw . . 








2 


00 


Fricassed 








2 


45 


Baked . 








3 


30 


Boiled . 








3 


30 


Boiled . 








2 


00 


Boiled . 








3 


00 


Boiled . . 








I 


3° 


Boiled . 








I 


00 


Raw . . 








2 


55 


Raw . . 








I 


30 


Boiled . 








3 


00 


Fried . . 








4 


00 


Broiled . . 








3 


00 


Boiled . 








4 


00 


Broiled . 








3 


20 


Boiled . 








2 


00 


Raw . . . 








2 


l S 


Baked . . 








2 


45 


Boiled . 








4 


00 



DIGESTION. 211 

17. Alcohol and the Stomach. — The action of alcohol on 
the stomach is that of an irritant. Having great affinity 
for water, it absorbs moisture from the tissues with which 
it comes in contact, and thus tends to parch and dry them. 
In all except minute quantities, it inflames the stomach ; 
and when taken habitually, or in large quantities, it 
injures or destroys some of the glands which secrete the 
mucous and the gastric fluids, and thickens and toughens 
the mucous lining. It also reduces the sensibility of the 
nerves of the stomach, paralyzing them to an extent that 
tends to render nervous and muscular action of the 
stomach less vigorous, and thus interferes with the pro- 
cess of digestion. 

18. In the case of St. Martin, Dr. Beaumont observed 
that " the free use of ardent spirits, wine, beer, or any 
other intoxicating liquors, when continued for some days, 
produced a state of inflammation and ulceration in the 
lining membrane, and change of the gastric juice;" and 
Dr. Albert Day, an eminent writer and authority on 
alcoholic diseases, says : " There is no appearance, after 
death, more common in the confirmed drunkard, who per- 
ishes after a long continuance of this habit, than a state 
of chronic inflammation of the lining membrane of the 
stomach. In this condition the walls of the organ are 
sometimes considerably thickened, are covered in their 
interior with a net-work of vessels closely injected with 
blood, and may present more or less extensive traces of 
ulceration. The thickening of the coats of the stomach 
may proceed to such an extent as to interrupt the passage 
of food', through mechanical impediment." It is evident, 
therefore, that the normal condition of the stomach of 
the habitual drinker of alcoholic liquids is greatly affected, 



212 ACADEMIC PHYSIOLOGY. 

and hence that the functions and usefulness of the stomach 
are proportionately impaired by alcohol. 

19. Alcohol and Digestion. — The Gastric Juice. — Alcohol 
when taken into the stomach excites a profuse flow 
of gastric juice; and as a large amount of gastric juice 
no doubt digests food more rapidly than a small amount, 
it has been argued that alcohol aids digestion by pro- 
voking an increased secretion of that juice. This may 
be its effect when taken in minute doses and during a 
limited period. But the secretion of gastric juice should 
be a natural process ; it should not be the outcome of an 
extortion which involves exhaustion and waste. In the 
words of an eminent writer, " Alcohol, though apparently 
helpful at the moment by procuring a profuse flow of 
gastric juice, secures this temporary effect at the cost of 
great waste of this precious fluid." If alcohol is habitu- 
ally taken, it constantly overtaxes the natural resources of 
the blood from which the gastric juice is derived, thus 
impoverishing the blood, and, consequently, degenerating 
the gastric juice and impairing digestion. 

20. But furthermore, alcohol in the stomach absorbs 
water from the gastric juice and precipitates the pepsin, 
thus separating it from the juice. 1 Deprived in this way 
of much of its chief solvent principle, the gastric juice 
is more or less unfitted for its office. The gastric juice is 
incapable of altering alcohol, and the latter is absorbed 
by the vessels of the stomach and passes into the blood 
unchanged. 

1 Take the stomach of a calf or of a pig that has just been killed, rinse the 
gastric juice out of it with a very small quantity of water, and put the liquid into a 
small bottle. The liquid will be milk-white, and, if a small quantity of alcohol is 
poured into it, the white portion will settle to the bottom. This white sediment con- 
tains the pepsin. 



DIGESTION. 213 

21. In other than very small quantities, it arrests the 
digestion of albuminoid food by shrinking and toughening 
it, thus rendering it insoluble. As the chemical action of 
alcohol on organic substances retards change in them, and 
because of its effects on the gastric juice and the nerves 
and muscles of the stomach, imperfectly digested food 
will pass through the pyloric valve into the small intes- 
tine. It follows, therefore, that the habitual drinking of 
alcoholic liquors impairs digestion ; and impaired digestion 
often becomes chronic indigestion with its numerous 
train of diseases, — inflammation of the stomach and of 
the bowels, diarrhoea, constipation, etc. 

22. Alcohol and Thirst. — It is well known that thirst is 
"an unfailing sequel " to the drinking of alcoholic liquor. 
In this fact we have proof that alcohol is not a true 
beverage. All true beverages furnish water to the blood 
and tissues, and thus slake thirst. Alcohol, on the con- 
trary, absorbs water from the tissues, and produces thirst. 
It is true that beer and other beverages which contain a 
large amount of water and a small quantity of alcohol 
allay thirst to a considerable extent ; but the water of 
these drinks would quench thirst more readily in the 
absence of the alcohol. 

23. Alcohol and the Accumulaion of Fat. — The maintenance 
of perfect health requires that certain constructive and 
destructive changes shall take place in the body with per- 
fect regularity and uniformity. In the words of Dr. Yeo, 
" If there is a disturbance in the constructive changes, 
the fabric suffers, and loss of strength must follow ; if 
there is disturbance of the destructive changes, the injury 
to the health of the body may not be so immediately 
apparent, but it will be felt, sooner or later. Mere excess 



214 ACADEMIC PHYSIOLOGY. 

of food, or an improper method of feeding, may be the 
cause of some of these disturbances. Thus it is easy to 
understand how corpulence arises. Something is regu- 
larly taken into the system which is not needed for con- 
struction or maintenance. If this excess were got rid of 
in a regular and normal manner, nothing remarkable would 
arise. But in some organizations there is a tendency not 
to turn this excess into substances which can readily be 
discharged from the body, but to throw it aside, as it 
were, within the body in the form of fat." 

24. It is true that certain persons who habitually drink 
alcoholic beverages which contain saccharine matter in- 
crease in fat and weight. But the fat in such instances is 
formed of particles of aliment which have been alcohol- 
ized, and which, while not adapted for use in the body, 
have not been reduced to a form in which they can be 
excreted from it ; hence they are held in the form of fat 
by the tissues. True nutrition is a replenishment of the 
tissues, and is not a mere accumulation of fat. Excessive 
accumulation of fat is a disease ; and when the fattening 
process extends, as it often does, into the interior of the 
body, there are produced the diseases known as fatty de- 
generation of the heart, liver, kidneys, etc. 

25. The fat of the beer-drinker is not so much an 
indication of healthful nutrition as it is of deficient excre- 
tion. Excessive fat adds no strength to bone, nerve, or 
muscle. In appearance the beer-drinker may be " a pic- 
ture of health," but in reality he is most incapable of 
resisting disease. Fatty deposits, diminished circulation, 
congestions, and disturbance of the functions of the 
stomach, liver, and kidneys, are, one or all, commonly 
present. Injuries, which to another would be but trivial 



DIGESTION. 215 

in results, are apt to lead to serious complications in him ; 
and when it is necessary to perform surgical operations 
upon the habitual drinker, the risk of a fatal result is much 
greater than in the case of a temperate person. 

26. Effects of Tobacco upon Digestion. — Chewing and smok- 
ing of tobacco overtask the salivary glands, and both viti- 
ate and exhaust their secretion. The digestive process 
dependent upon the action of the saliva must be greatly 
retarded in consequence of the great waste of that fluid, 
caused by its being expectorated from the mouth. The 
poisonous nicotine is absorbed by the mucous membrane 
of the mouth, stomach, etc., and enters the blood, produ- 
cing nausea and prostration. 

27. The alimentary canal suffers by the greater or less 
quantity of tobacco juice swallowed with the saliva, in 
either smoking or chewing the weed, producing loss of 
tone in the stomach, failure of appetite, indigestion, and 
constipation. Its poisonous property is due to the active 
principle, nicotia, which in its free state is an extremely 
powerful and deadly poison, " proving fatal sooner than 
any other excepting prussic acid." 

28. Like alcohol and other narcotics, tobacco begets a 
depraved appetite to which the strongest wills yield and 
become enslaved. It attacks the blood, increasing its flu- 
idity and causing resistance to coagulation. Its vitiating 
effects upon the blood result in harm to the brain and 
nerves ; and nervousness, languor, disturbed sleep, and 
mental depression are common effects of its action on the 
nervous system. 



2l6 ACADEMIC PHYSIOLOGY. 

CHAPTER XXIII. 

CHYLIFICATION, OR INTESTINAL DIGESTION. 

1. Difficulty of Investigation. — We now follow the progress 
of the chyme from the stomach into the intestines, and 
note the changes that are effected in it, which are collec- 
tively known as cJiylification, or intestinal digestion. 

2. The opportunities for observation or investigation 
of the digestive processes carried on in the intestines of 
human beings have been very limited, and are attended 
with great difficulties ; and hence, comparatively little 
progress has been made towards ascertaining exactly how 
digestion is completed, the functions of various organs, 
and the action of the digestive juices. Almost all our 
exact knowledge of the intestinal processes has been ob- 
tained by experiments on animals. 

3. The Intestines. — The intestines are continuous with 
the stomach, and form one long tube having mucous, mus- 
cular, and peritoneal coats like the stomach. The perito- 
neal coat is reflected off from the back of the tube, in its 
entire length, and attaches it to the spinal column by a 
double fold of membrane, called the mesentery. The intes- 
tinal tube is divided anatomically into the small intestines 
and the lai-ge intestine, the latter having a larger diame- 
ter than the former. The valve, or opening of the small 
intestine into the large one, is situated in the region of 
the right groin ; and while it permits the passage of sub- 
stances from the former into the latter, it opposes their 
passage in the opposite direction. 



DIGESTION. 217 

4. The Small Intestine. — The small intestine is sub-di- 
vided into three parts, viz., the duodenum, the jejunum, 
and the ileum ; but there is no actual line of separation 
between these, and the names indicate merely an arbitrary 
distinction made by the ancient anatomists. 

5. The duodenum is that part of the small intestine 
which immediately succeeds the stomach, and it is so 
named because it measures nearly twelve finger-breadths 
in length. It is bent into a loop,, and is fastened to the 
back wall of the abdomen. 

6. The jejunum is the intermediate section of the small 
intestine, and its numerous coils occupy the central region 
of the abdomen. 

7. The ileum is that section of the small intestine which 
opens into the large one by a valve (the ileo-ccecal valve) 
to which reference has been made. The length of the 
small intestine is about twenty-five feet. 

8. The Large Intestine. — The large intestine is divided, 
for convenience of description, into three parts, called 
respectively the ccecum, the colon, and the rectum. 

9. The ccecum is the pouch-like enlargement situated in 
the lower part of the right side of the abdomen, and into 
which the small intestine opens. Attached to the caecum 
is a peculiar, slender, projecting tube, which, from its 
form, is called the vermiform appendix, i.e., the worm-like 
appendage, and for which there is no known use. It is a 
constant source of danger from the fact that the small 
seeds of berries and other fruits occasionally find lodge- 
ment in it, causing irritation which results in the forma- 
tion of an abscess and the destruction of life. 

10. The colon constitutes the greater part of the large 
intestine. It is sub-divided into three sections, viz., the 



218 



ACADEMIC PHYSIOLOGY. 



ascending colon, which rises from the caecum and extends 
upward on the right side of the abdomen, nearly to the 
stomach ; the transverse colon, which extends, across to- 
ward the left, below the stomach ; and the descending 

colon, which extends down- 
ward on the left side. 
Reaching the middle line, 
the colon becomes the rec- 
tum, which is the last divis- 
ion of the large intestine 
and the termination of the 
intestinal canal. The length 
of the large intestine is 
about five feet. 

11. The Interior of the In- 

Fig. 42. Semi-diagrammatic View of Two 
Villi of the Small Intestines. {Magnified testines. The mUCOUS COat, 

or lining of the intestines, 
is thrown into numerous 
shelf-like folds, which, from 




EXPLANATION. 



a, substance of the villus ; b, its epithelium, 
of which some cells are seen detached at b 1 ; 

cd, the artery and vein, with their connect- their winking Or Wave-like 
ing capillary network, which envelops and , • ,i n ' -\ r ^.1 

hides,, the lacteal, which occupies tlJ = centre m ° tl0n 1T1 tfte fluidS ° f the 

of the villus and opens into a network of intestine, are Called Valvill(E 
lacteal vessels at its base. . „-,. r i i 

conniventes. 1 nese tolas or 
valves form arches which encircle about three-fourths 
of the intestine, and are of use in retarding the passage 
of food along the canal, thus affording the absorbent 
vessels a better opportunity to imbibe nutritious matter. 
They also increase the extent of the secreting and 
absorbent surface. The mucous coat is penetrated 
almost to its surface by minute blood-vessels and absorb- 
ent vessels, which, in many places, are covered only by a 
very thin layer of delicate membrane. 



DIGESTION. 



219 



12. Upon the surface of the mucous coat are almost 
innumerable hair-like projections which present a plush- 
like appearance, and are known as villi (L., meaning 
closely set hairs). The estimated number of these is about 
10,000,000. Each villus contains numerous little blood- 
vessels, which doubtless absorb certain fluid products of 
digestion and empty them into the portal vein, by which 
they are conveyed to the liver and thence to the heart. 

13. Lacteals. — In the interior of each villus are also the 
finest twigs of one or more lacteals (L. lac, milk) — ves- 

TD 

EXPLANATION. 

A portion of the thoracic duct, marked 
T D above, and T D below, lying in front of 
and in contact with the spine, S. 

By the side of I I, is seen a portion of ^ 
intestine attached to the mesentery, a kind 
of membranous rtiffle, around the border 
of which the entire tube of the intestine is 
fastened. 

L L show a lacteal vessel running from the 
inside of the intestine, charged with a milky 
fluid which is conducted into the mesenteric 
glands, seen lying between the two folds of 
that membrane. In these the chyle is essen- 
tially changed in character, and perhaps re- 
ceives additional fluid from the gland itself. 
From these the fluid next passes on through 
the excretory ducts, M M, which join the 
main trunk of the thoracic duct. 



s..Cfl 



MG^ 




TD^~ 



sels having club-shaped, and probably closed, extremities. 
The lacteals are absorbent vessels belonging to the great 
system of lymphatics which are found everywhere in the 
body. The milk-white appearance of the lacteals, when 
filled with the digested matter which they absorb from 
the canal, suggests their name. These vessels combine 
with each other, and form a network from the meshes of 
which proceed branches. These branches, successively 



220 ACADEMIC PHYSIOLOGY. 

uniting, form larger trunks which finally pass out through 
both mucous and muscular coats, and, after again uniting, 
terminate in a small oval sac, called the receptaculum chyli 
(receptacle of the chyle), which is situated in front of the 
vertebrae of the loins. From this sac the thoracic duct, 
"a tube quill-like in size," extends upwards in front of 
the spinal column, and opens into the left subclavian vein 
(the large vein under the left collar-bone), pouring its 
contents into the venous blood just as it is about entering 
the right side of the heart. 

14. Intestinal Glands. — In the mucous coat of the intes- 
tine are numerous glands, some of which secrete and pour 
out mucus, and others digestive fluids. These secretions 
combine to form what is termed the intestinal juice. 
Into the duodenum two peculiar fluids are conveyed by a 
common duct, one of whose branches brings in bile from 
the liver, and the other the pancreatic juice from the 
pancreas. 

15. The Liver. — The liver is the largest gland of the 
body ; and it weighs, in health, from three to four pounds. 
It secretes from the blood a bitter fluid called bile, which, 
during the intervals of digestion, is stored up in the gall 
bladder upon the under side of the liver. While the liver 
is evidently a very important organ, still its precise use 
and functions are not well known, and are subjects of dis- 
pute and doubt. The special office which the bile per- 
forms in relation to digestion is even yet a controverted 
point. Animals have been subjected to operations which, 
while not interfering with the action of the liver, pre- 
vented the bile from entering the intestine. It was found 
that, although the appetite and digestion of animals thus 
treated remained good, yet they soon became emaciated 



DIGESTION. 221 

and died of apparent starvation. This fact has led to the 
conclusion that the bile performs some specially impor- 
tant office in the nutrition of the body, and is not merely 
an excrementitious fluid to be discharged from it. 

16. It is also believed that the liver secretes sugar from 
the fluids of the portal vein, and that this sugar is decom- 
posed and disappears in the process of nutrition. 

17. The Pancreas. — The pancreas, or sweet-break 1 , is a 
gland about six inches long, and is situated behind the 
stomach. It secretes the pancreatic juice, which by ex- 
periment has been proven to be a chief agent in the 
digestion of fatty portions of the food, breaking them up 
into minute particles which are in condition to be ab- 
sorbed by the vessels of the intestine. 

18. The Spleen. — This is a spongy gland situated at the 
left extremity of the stomach, just under the false ribs. 
It has remained an unsolved puzzle to physiologists, and 
its use and functions are yet to be discovered. The 
ancients believed it to be the seat of anger and melancholy. 
It is a remarkable fact that the spleen may be entirely 
removed from animals without lasting injury to their 
health. A dog when thus treated recovers rapidly from 
the wound, increases in appetite and flesh, and exhibits 
unusual ferocity. A large artery supplies the spleen with 
blood, and its veins empty into the portal vein and thence 
into the liver. A recent and plausible supposition is, 
that the spleen may be employed in the formation of new 
blood corpuscles, and in the destruction of old ones. 

19. Chylification. — The function of the small intestine is 
more than a merely mechanical one. The process of diges- 
tion, begun in the mouth and carried on so actively in the 
stomach, is here continued. In a physiological sense, 



222 ACADEMIC PHYSIOLOGY. 

the duodenum may be regarded as a second stomach, the 
jejunum as a third, and it would scarcely enter the field of 
imagination to regard the ileum as a fourth ; for through- 
out the whole length of the small intestine the process of 
digestion goes on, a solvent fluid being secreted in vary- 
ing quantities along its whole inner surface. 

20. In the duodenum the chyme is mixed not only with 
the intestinal juice, but also with the pancreatic juice and 
the bile. The pancreatic juice probably completes the 
work of the saliva by converting into sugar such particles 
of starch as escaped digestion in the mouth, and also 
breaks up fatty matter into minute globules. The bile 
also, being alkaline, is believed to have an effect similar 
to that of the pancreatic juice in separating fatty sub- 
stances into minute particles, and also that it neutralizes 
the acid contained in the chyme. The intestinal juice, 
secreted by millions of glands, is so mixed with the other 
digestive juices that but little is known of its special 
effects. It probably possesses a feeble digestive property, 
and it is both affirmed and denied that this juice changes 
starch into sugar. 

21. During digestion the various digestive fluids are 
secreted, poured out, and re-absorbed with great energy 
and in large quantities. No portion of the food can be 
absorbed except in complete solution, and such solution is 
effected by the chemical action of the digestive juices. 
Their nature, in combination, is alkaline ; and by their 
united action the chyme is converted into a milky 
fluid, called chyle, which is readily absorbed into the 
blood. 

22. Absorption of the Chyle. — The encircling muscular 
fibres, of the small intestine contract from above down- 



DIGESTION. 223 

ward, with a wave-like movement, and propel the chyle 
along the canal, being aided in this by the action of the 
longitudinal fibres. This action of the intestine is termed 
its vermicular motion, i.e., worm-like motion. 

23. The villi projecting from the lining membrane of 
the intestine sway about in the chyle, and absorb, or (as 
recent researches seem to indicate) draw by a pump-like 
action, the creamy portions of the nutritious fluid into the 
ends of the lacteal vessels in their interior. Conducted 
by the lacteals into the receptaculum chyli, and from that 
sac by the thoracic duct into the left subclavian vein, the 
chyle is poured with the venous blood into the right side 
of the heart. The network of blood-vessels of the intes- 
tine also takes up and carries into the blood large por- 
tions of the chyle. On entering the heart, the chyle 
in conjunction with the venous blood is pumped into 
the lungs, and is there converted into perfect or 
arterial blood, "fit for the highest processes of organi- 
zation." 

24. Evils of Indigestion. — Certain portions of the food 
eaten are not capable of complete digestion, and, being 
insoluble, cannot supply the wants of the tissues. It is 
the function of the large intestine to secrete effete matters 
from the blood, and to expel these and the innutritious 
or waste portions of the aliment. 

" When effete matter is retained a moment beyond the 
time its expulsion is demanded, the absorbents carry some 
of the more fluid portions of the poisonous mass into 
the circulation, and they become diffused throughout 
the body. The more solid portions, by pressure upon the 
small blood-vessels, cut off the circulation in them, caus- 
ing painful engorgements known as hemorrhoids. But 



224 ACADEMIC PHYSIOLOGY. 

the trouble is seldom confined here. As a result of the 
blood-poisoning, there is almost invariably more or less 
dyspepsia, derangement of the functions of the heart, 
liver, and kidneys, accompanied by headache and nervous 
debility, often verging on paralysis." 

25. General Anaemia. — The term aticemia signifies, liter- 
ally, bloodlessness, and is used to indicate a condition of 
the system in which the blood is impoverished or deficient 
in its nutritive constituents. This condition is princi- 
pally due to insufficient food or to imperfect digestion 
and assimilation; but it may occur from a lack of oxygen 
in the system, even though the quantity of food and its 
digestion are apparently normal. It may therefore be 
said that a sufficient supply of food of proper quality, 
fresh air, exercise, and natural sleep must operate together 
in preventing anaemia. Business worry, dissipation, the 
intemperate use of alcoholic drink and tobacco, are com- 
mon exciting causes among men. 



Suggested Points for Questions. 

Chapter XVI. — i. Necessity of food — waste and repair. 2. Food as 
fuel — energy, life, repair. 3-4. Hunger and thirst — nature, indicative, 
time endured respectively. 5. A true food defined; carbon, hydrogen, oxy- 
gen, and nitrogen as elements; other elements — inorganic; elements of the 
body; basis of classification of foods; nutritive values influenced; names of 
classes of food-stuffs. 6, 7, 8. Proteids or nitrogenous foods — nitrogen as a 
gas and as a solid; importance as an element, effect of deprivation; from 
what obtained; chief nitrogenous substances — similarity in animal and vege- 
table; animal or vegetable food, which? 9. Fats or oils as food, importance 
of, when and where, chief office, composition of. 10. Non-nitrogenous food — 
nourishing properties, theories of modern chemists. II. Amyloids or starches 
— comprise what, non-nitrogenous, other elements, quantity employed, prod- 



SUGGESTED POINTS FOR QUESTIONS. 225 

ucts of what, in what found, contributive, importance, peculiarity of starch. 
12. Water and other mineral foods — amount of water in body, office of, loss 
of and compensation for; water in solid food, quantity ordinarily needed, 
vast quantity taken accounted for, importance of purity. 13. Mineral salts 

— quantity in tissues, whence obtained, deficiency of — effects. 14. Com- 
mon salt — importance of, flavoring, appetite and digestion affected; ani- 
mals seek salt, effects of deprivation. 15, 16. Necessity for mixed diet — 
single articles incomplete in elements — examples; excess and deficiency in 
a single article — example of meat, bread; effects of deficiency or excess in 
elements; a varied diet; confinement to a single article — effects; effects of 
concentrated food; bulk required — reason; concentrated food combined with 
bulky; system misses any element; change of diet may benefit; longing — 
cause. 17. Quantity of different food-elements required daily — penalty of 
taking less; excess — results. 18. Conditions affecting increase or decrease. 

Chap. XVII. — I. Vegetable food-articles most common; important 
constituents — starch, fat, nitrogenous, etc. 2. Wheat — constituents, nutri- 
tious value. 3. Rye — compared with wheat, point of inferiority, where 
much used, "spurred rye" poisonous, whiskey from rye. 4. Oatmeal — 
richness, extent of use, desirability. 5. Cornmeal — extensively used, value, 
deficiencies, especial richness; hominy. 6. Rice — nativity, chief food of 
millions, nutritive value, deficiencies, use in warm climates, digestibility — 
value to the sick, large quantity for nutrition — reason, preparation. 7. 
Barley — constituents compared with wheat — value. 8. Pease and beans — 
similarity to cereals, more nitrogen — casein, digestibility when dry, etc. — 
disturbances, nutritive value, deficiency. 9. Potatoes — nutritive value 
compared, nativity, etc., solid components, deficiencies — how compensated, 
new and old, cooking — sweet potatoes. 10. (Table of Composition.) II. 
Garden products — succulent vegetables, nutritive value, supply variety; 
salts; prevent scurvy. 12 Beets — richness, nutritive value. 13. Turnips, 
carrots, parsnips — chief constituent, other constituents — nutritive? 14. 
Cabbage and "greens" — nutriment small, value as food. 15-19. Tomatoes, 
asparagus, rhubarb, cauliflower, pumpkin, squash, — chief constituents and 
special value of each as food — deficiencies compensated in cooking. 20. 
Fruits — value chemically, beneficial, value in warm weather — cause, juice 
the most valuable — why; unripe, etc., and unwholesome. 21. Canned 
fruits — decomposition, poisoning by, character of cans. 22. Confectionery 

— nutritive value, pure, adulterated, kinds probably unwholesome; white 
candy. 

Chap. XVIII. — 1. Animal food — quantity, variety; alimentary princi- 
ples contained. 2. Animal bodies as food — chemical elements. 3. Meat — 



226 ACADEMIC PHYSIOLOGY. 

constituents; flesh of what animals preferable. 4. Circumstances affecting 
value of animal food — age of animal, preparation for market, quick fattening, 
slop-fed. 5. Manner of slaughtering, removal of blood, the Jewish method. 
6. Decomposition of meat, eaten soon when not frozen; tenderness of putre- 
faction — digestion related; breaking of fibres for tenderness — teeth in rela- 
tion. 7. Value affected by cooking — influence of proper cooking. 8. 
Meats pronounced unfit for food — conditions. 9. Properties of meats — 
beef, nutritive value, varying flavor, in different animals, special parts, 
color when wholesome or unwholesome, wet, inelastic. 10. Veal — 
value, digestibility, when unfit — effects. 1 1. Mutton — digestibility, nutri- 
ment, in dyspepsia, dysentery; lamb —compared with mutton. 12. Pork 

— importance as food — reason; heat-producing; nitrogenous matter com- 
pared with beef; unclean food of hogs — effects; liability to disease — 
trichina spiralis and effects of, destruction of. 13. Salt meats, dried 
meats — nature and values. 14. Fowl or poultry — digestibility compared, 
nutritive value, white meat; broth, flavor, nature, value; flesh of carnivorous 
birds — nature. 15. Fish — constituents and food value; pink flesh, white 
flesh — values; decomposition, unwholesomeness; appearance of stale fish; 
odor as a test. Lobsters and crabs — constituents, digestibility, rapid decom- 
position — danger. Clams — tough, indigestible. Oysters — nutriment, di- 
gestibility, flavor. Fish as a "brain food" — confirmed? 16, 17, 18. 
Milk — constituent elements, importance as a food; a food for children, 
adults; varying composition — causes; improper feeding of cows — result; 
"barn-yard milk." Adulteration of milk — methods, detection of; skimmed 
milk — innutritious — test. Care of milk — absorption of gases, germs, dust 

— prevention; metallic vessels — acid effects and poison generated; scalding 
of vessels. 19. Disease transmitted by milk — diseased cows, fermentation, 
infected by disease germs, epidemic disease from unwholesome milk — infec- 
tion from water used. 20. Preventives against disease from milk. 21. 
Butter and cheese — nutritive values, digestibility, casein, rancid butter, 
adulteration of butter, absorption of impurities; cheese nitrogenous, etc., 
quantity eaten — limited; strong and indigestible. 23. Eggs — value as 
food, constituents, deficiencies; digestibility influenced by cooking; preserv- 
ative methods. 24. Cooking — object of; results of poor cooking — un- 
palatable, innutritious, indigestible. 25. Cooking of meat — object to be 
attained, degree of heat at first — reason; broiling, roasting, baking — effec- 
tiveness, requisites; broiled meat digestible; boiling of meat — method, etc., 
making of soup — treatment of meat; frying as a method of cooking — 
objections, method, errors in process. 26. Cooking vegetables — philosophy 
of boiling; potatoes — boiling and baking of, nature of heat employed; 



SUGGESTED POINTS FOR QUESTIONS. 227 

deficiencies in fats compensated. 27. Mixing of bread — fermentation, 
through kneeding, limit of fermentation — reason, temperature of dough, and 
arrest of fermentation; unfermented bread, aerated bread. 28. Baking of 
bread — requisites of digestibility; underbaked, overbaked — effects; wrap- 
ping in wet cloths objectionable. Constituents of bread — deficiencies com- 
pensated. 29. Condiments — simple flavors few; lack of flavor in certain 
food articles; offices of condiments — classes; excessive use, injurious adul- 
teration — examples. 

Chap. XIX. — I. Physiological offices of water — the instrument of 
change — solvent power; purity essential, appearances deceptive; pure water 
rare; pollution prevented. 2. Chief impurities — effects; varieties of water 

— hard, soft, etc. — causes. 3,4. Rain-water — source, impurities — gases, 
soot, etc.; corrupting substances from exposed surfaces — putrefaction; con- 
taminated by pipes, foul cisterns, etc.; clean cisterns — structure; properties 
of rain-water — when best of all. 5, 6. River, or surface water — source of 
supply, nature of impurities, character of strata, condition of surface of 
ground — effects; effects of sewage; few pure rivers in settled regions; purifi- 
cation of running streams; specific poisons carried; objection to river-water 

— pollution, examples (note). 6. Water of ponds, small streams, etc. — 
cause of impurities, diseases from; instance of typhoid fever epidemic. 
7, 8, 9, 10. Spring water — nature, temperature, agreeable properties, essen- 
tials for purity, maybe impure. Well water — shallow wells impure — cause; 
filth — sodden earth — percolation fails to remove impurity; influence of cess- 
pools, stables, etc. Filth-soaked ground in cities — wells polluted. Deep 
wells — nature of water, prevention of drainage from surface, disease and 
death from carelessness in drainage — duties. 11, 12. Hardness of water — 
nature, cause, effects on boilers, etc., cooking with. Evidence of injury to 
health; soft water better. 13. Water and lead-poisoning; coating of pipes 
by hard water; use of water from lead pipes — caution. 14-18. Means of 
purifying water — process of filtration, distillation, boiling, freezing, and 
efficacy of each; construction of simple filter — manipulation. 19. Detection 
of impure water — senses unreliable. 20. Temperature of water-supply, 
effects — example. 21. Cooling of water — process. 

Chap. XX. — 1. General classes of drink; artificial drinks — inducement 
to use, liable to injure. 2, 3. Tea — constituents-, nature, effects, varieties, 
use in China — reason; " tea tasters " and packers affected; value — dietetic 
and medicinal; stimulant — injurious to youth and nervous adults; in heart 
disease; to cause wakefulness — result. 4, 5. Coffee — constituent princi- 
ples; exhilarating power, general effects. Tea and coffee — foods? lessening 
waste — consequence; relied on as food — result; Dr. Hayes's statement. 



228 ACADEMIC PHYSIOLOGY. 

6. Cocoa — source, constituents; stimulating and nutritive properties. 7, 8, 
9. Adulterations of tea, coffee, and cocoa — methods, and extent. 10. 
Alcoholic beverages defined; alcohol — production, sources, materials. 12. 
Fermentation described. 13. Malting described — product. 14 Fermented 
liquors named, described, and quantity of alcohol stated. 15. Distilled 
liquors in common use named; source of; distillation described; distilled 
liquors — source of each, characteristics, coloring, etc., amount of alcohol 
contained. 16. Other constituents of alcoholic beverages — alcohol the active 
element; attractiveness, tonic properties compared. 17. Adulteration of 
alcoholic beverages — purity exceptional, adulteration alarming and shameful 

— evil consequences; substances employed. 18-20. Alcohol and its proper- 
ties — color, odor, taste, volatile and inflammable, solvent powers, use in arts 
and sciences, etc.; affinity for water — antiseptic properties; allaying pain — 
deadening sensibility; physicians cautious in prescribing alcohol — reason. 
21. Alcohol as a beverage and as a poison — nature of a true beverage; affinity 
for and extraction of water — thirst created; action of alcohol when dilute 
and when strong — blistering, disorganizing tissues, thirst-creating. 22. 
Alcohol and albuminous elements of food — arresting digestion. 23. Alco- 
hol's general effects on nerve-centres, intestines, digestion, blood — final 
results of dram-drinking. 24. Considerable quantity taken during or after 
eating — effects on digestion; results of continuance; taken before labor of the 
day — harm. 25. Misery inflicted. 

Chap. XXI. — 1. Digestion defined; when perfect — importance. 2. 
Ill-temper, etc., arising from indigestion; violation of simple laws — results. 
3. Organs named — appendages. 4. Alimentary canal described — mem- 
brane, secretions, juices, coats, etc. 5. Peritoneum described — mesentery. 
6. Processes named in order. 7. Mutual dependence of processes. 8-12. 
Mastication — organs, importance, process — movements; forms of teeth — 
purpose; mastication and the will, preventing disorders, manner of eating; 
comments of the Lancet on mastication; toothless stomach. 13. Insalivation 

— importance, moistening not the sole purpose, chemical action, definition. 
14-18. Salivary glands, location, number, structure, each named and de- 
scribed (size, ducts, location); functions, saliva; exciting the glands to 
action — solid food and mastication. 19, 20. Nature and action of saliva — 
color, etc., alkaline nature, daily amount; action or use — mechanical, chemi- 
cal; action on starch — importance hence; other liquids not effective substi- 
tutes; saliva — proteids and fats. 21. Effects of tobacco on salivary digestion 

— dryness, thirst, waste, depraved secretion — sewers. 22. Acids and salivary 
digestion — delay, influence in health and disease, reducing corpulence. 
23-25. Deglutition — definition, process — pharynx, soft palate, sesophagus, 



SUGGESTED POINTS FOR QUESTIONS. 229 

constrictors; closure of wind-pipe in swallowing — rapidity important; 
oesophagus — structure, action of muscles. 

Chap. XXII. — 1-5. Chymification — form and location of stomach, 
capacity; orifices, valves and their functions, curvatures; coats — mucous, 
muscular, peritoneal — rugae, gastric glands and tubes and their offices, mus- 
cular structure and movements, attachment and support. 6-8. Gastric 
juice — changes caused by, acid nature, elements — pepsin, etc., importance 
of; action of gastric juice on proteids — peptones, on fat, starch, and sugar; 
quantity of gastric juice — while fasting, when aliment is taken. 9. Stomach 
digestion — a closed chamber, contractions and movements of food; arrange- 
ment of food in stomach, change in mucous, lining and flow of juice, move- 
ments and changes observed by Dr. Beaumont, resolution into chyme, 
accumulation, action of pylorus; temperature of stomach — influence of cold 
liquids on digestion. 14. Absorption from the stomach — peptone, saccharine 
fluid, conveyance by portal vein to liver, etc. 15, 16. Time required for 
stomach digestion — varying with food, bulk, health — maximum; relation of 
rapid digestion to nutrition, delayed digestion. 17, 18. Effects of alcohol on 
the stomach — irritation, affinity for water — parching, destroying glands, 
tongue's lining, paralyzing nerves and vigor, etc.; observations of Dr. Beau- 
mont in case of St. Martin, and of Dr. Day relative to inflammation, thicken- 
ing of membrane, congestion, interruption of movement of food, etc. 19-21. 
Alcohol and digestion — flow of gastric juice should be natural — extortion, 
exhaustion, impaired digestion; absorbs water — pepsin affected, juice unfitted, 
alcohol unchanged enters blood; albuminoid food toughened, retarded change, 
undigested food, train of diseases. 22. Alcohol and thirst — absorption of 
water from tissues, and thirst, thirst-quenching alcoholic beverages — water 
superior. 23-25. Alcohol and accumulation of fat — waste and repair should 
be uniform, effects of disturbance, cause of corpulence, deficient change and 
excretion — fat; accumulation of alchoholized particles — fat, true nutrition, 
excessive fat a disease —fatty degeneration; beer-drinkers' fat, no strength 
added, disease induced — instances, complications in case of injury — surgical 
operations rendered dangerous. 26-28. Effects of tobacco on digestion — 
salivary glands overtaxed, etc., waste and salivary digestion, nicotine absorbed 

— effect; swallowing tobacco juice — effect; nicotia a deadly poison; depraved 
appetite — will enslaved, effect on blood, brain, nerves — nervousness, 
languor, disturbed sleep, etc. 

Chap. XXIII. — 1, 2. Chylification — difficulty of investigation, knowl- 
edge obtained by experiment on lower animals. 3. The intestines described 

— coats, attachment to spine — mesentery, the small and the large intestine 

— valve connecting and its function. 4-7. Divisions of small intestine — 



23O ACADEMIC PHYSIOLOGY. 

names, location, form, direction, total length. 8-10. Large intestine — 
divisions, location, form, peculiarities; caecum — vermiform appendix — use, 
danger; divisions of the colon; the rectum; total length. 11, 12. interior of 
intestines — mucous coat, folds and motion — office, blood-vessels, absorb- 
ents — covering; villi — number and function. 13. Lacteals — location, 
shape, structure, appearance, office; ramification of trunks; receptacle of 
chyle, thoracic duct, chyle conducted to subclavian vein enters heart. 14. 
Intestinal glands — secretion and nature of; bile, pancreatic juice — sources. 
15, 16. The liver — size, secretion, gall-bladder; functions of liver — 
doubt; office of bile — result of experiments on an animal, etc.; liver secretes 
sugar. 17. Pancreas — location, pancreatic juice — office. 18. Spleen — 
location, functions unknown, ancient belief, effects of removal from animals; 
plausible theory of office. 19-21. Chylification — function of small intes- 
tine — digestion; secretion throughout length; digestion in duodenum — 
entry of juices, and their action; probable action of bile — alkaline; action 
of pancreatic juice; action of the intestinal juices; quantity poured out and 
re-absorbed; food in solution — absorption; nature of juices combined — 
alkaline; result of action — chyle. 22, 23. Absorption of chyle — action of 
intestine, of the villi, conduction to heart, entering venous blood, pumped to 
lungs — arterialized blood. 24. Evils of indigestion — insoluble elements, 
effete matters secreted and expelled — function of intestine; undue retention 
of effete products — effects. 25. General anaemia defined — <■ causes in gen- 
eral — prevention; special causes — alcohol, tobacco, etc. 



THE NERVOUS SYSTEM. 



231 




Fig. 44. The Cerebrospinal System. 
A, cerebrum; B, cerebellum ; S, spinal cord; C, Cauda equina ; D, great sciatic nerve. 



THE NERVOUS SYSTEM. 



CHAPTER XXIV. 

THE NERVOUS SYSTEM. THE BRAIN. 

1. Functions of the Nervous System. — Every movement of 
the body, whether voluntary or involuntary, is caused and 
governed by some portion of the nervous system. If we 
will to do anything, we do it through the agency of 
nervous matter which acts as a medium between the mind 
and the muscles. Nerve-matter does not produce motion 
by its own contraction, but by its mysterious influence 
over the muscles in which its fibres terminate. Not only 
every motion, but also every sensation, is dependent upon 
it. The material of which the nervous system is com- 
posed constitutes the highest order of organized matter, 
and in some mysterious way possesses the hidden force or 
power which constitutes what is called life. 

2. Divisions of the Nervous System. — The nervous system 
consists of two connected parts, called the cerebrospinal 
system and the sympathetic system. 

3. The cerebrospinal system consists of the brain, the 

spmal cord, and all the nerves given off from the brain 

and the cord. The nerves of this system are distributed 

chiefly to the voluntary muscles, the skin, and to the 

232 



THE NERVOUS SYSTEM. 233 

other organs of the senses, — the eye, ear, nose, and 
tongue. 

4. The sympathetic system consists of a number of 
ganglia (knots) of nerve-matter, connected by intervening 
nerve cords, which are situated on each side of the 
vertebral column, and extend from the base of the skull to 
the end of the column. The nerves of this system pass 
off in various directions to internal organs of the body, — 
the stomach, heart, blood-vessels, etc., — control involun- 
tary movements, and regulate the supply of blood to the 
various parts. Some of the nerve branches form com- 
munication with the cerebro-spinal system. 

5. Nervous Tissue. — Examination of the substance of 
which the nervous system is composed reveals two kinds 
of matter, which, on account of their color, are called the 
gray matter and the white matter. 

6. The gray matter presides over all mental action and 
sensation, while the white matter imparts motion to the 
muscular tissues to which it is supplied. 

7. There is a fundamental difference in structure 
between the gray and the white matter. The white 
matter consists entirely of nerve-fibres supported in a 
delicate framework of connective tissue and accom- 
panied by blood-vessels. The gray matter contains in 
addition a number of nerve-cells, some of which are of 
considerable size. These cells are entirely absent in the 
white matter. The gray matter is pulpy and softer than 
the white, and the white greatly exceeds the gray in total 
amount. 

8. The Brain. — The brain, the great netve-centre of the 
body, is the large, upper portion of the cerebro-spinal sys- 
tem filling the cavity of the skull. It consists chiefly of 



234 ACADEMIC PHYSIOLOGY. 

soft nerve-substance, the gray matter situated on the ex- 
ternal surface and the white matter located internally. 
It is the seat not only of the nervous force which regu- 
lates the whole body, but is also the throne of the intel- 
lect and the home of the emotions. 

9. The average weight of the human brain in the adult 
male is about 48 ounces, and in the female 44 ounces. 
The maximum weight in the male, in a large number of 
cases, has been found to be 65 ounces, and the minimum 
34 ounces ; the maximum in the female" 56 ounces, and 
the minimum 31 ounces. The human brain is larger than 
that of any of the lower animals except the elephant and 
the whale, the brain of the former weighing from eight to 
ten pounds, that of the latter somewhat more than five 
pounds. While the brains of these animals are larger 
than the human brain, they are not so finely organized ; 
and to this latter fact the human brain owes its superior 
intellectual power. Indeed, the varying mental capacity 
of different individuals is due to the texture or organization 
of the brain rather than to its volume or weight, within 
certain limits. It does not necessarily follow that, because 
an individual is physically a giant and has a brain propor- 
tionately large, he is therefore intellectually a giant. 

10. To protect the brain substance from pressure and 
injury, three membranes are interposed between it and the 
inner surface of the skull. First, the surface of the brain 
is covered with a very thin and delicate membrane called 
the pia mater (Lat., pious mother), which consists of a 
thickly meshed network of small arteries and veins sup- 
ported by connective tissue. From this membrane the 
brain receives its supply of blood. Second, a delicate and 
transparent membrane called the arachnoid membrane (Gr. 



THE NERVOUS SYSTEM. 235 

arachne, a spider's web ; and eidos, form), consisting of two 
layers, one of which covers the pia mater, and the other 
reflected over the under surface of the next upper mem- 
brane. In this way it forms a closed sac which contains a 
certain amount of liquid and acts as a cushion. Finally, 
over this is the third membrane, the dura mater (Lat., hard 
mother), which is tough and fibrous. Its outer surface is 
rough, and is in contact with the inner surface of the skull ; 
its inner surface is smooth and in contact with the arachnoid 
below it. The surface of the brain is marked by a deep 
fissure passing from before backward, and thus divided into 
two lateral masses called the right and the left hemi- 
spheres. 

11. The brain consists of several parts, the chief of 
which are the cerebrum or greater brain, the cerebellum or 
lesser brain, the pons Varolii (Lat., pons, a bridge), and 
the medulla oblongata (Lat., oblong marrow). A descrip- 
tion of the structure and functions of each of these divis- 
ions follows : — 

12. The Cerebrum. — The cerebrum occupies all the upper 
and frontal portion of the cavity of the skull, and com- 
prises about nine-tenths of the weight of the entire brain. 
It consists of two hemispheres, the right and the left, and 
is composed of a thick layer of gray matter surrounding 
white, fibrous nerve-substance. The surface of the brain 
(the gray matter) is drawn up into numerous irregular 
folds or convolutions, by which its area is greatly in- 
creased. Beneath the layer of gray matter are found 
interlacing, white fibres, so intimately combined that the 
anatomist's knife is unable to separate them completely. 
In parts of the cerebrum these fibres cross and recross, 
and thus the parts of the brain are connected. It is from 



236 



ACADEMIC PHYSIOLOGY 



the crossing of these fibres in the centre of the brain that 
injuries upon its left side are manifested by paralysis on 
the right side of the body, and vice-versa. Wherever may 
be the exact seat of the motor principle, the brain exercises 
a cross-action on the muscles ; that is, the left hemisphere 
induces the movements of the right side of the body, and 
the right hemisphere those of the left. The white fibres 




CE 



CER 



Fig. 45. 

EXPLANATION. 

This figure represents the left half of the brain. CE, the cerebrum; CER, the cere- 
bellum; MO, the medulla oblongata ; OP, optic nerve ; SC, spinal cord ; AV, arbor vitae. 

of the brain also pass down to the spinal cord and conduct 
the impulses of motion. Other fibres coming up from the 
cord convey sensory impulses to the gray matter. Thus 
there is seen to be a circuit as in a telegraphic system — 
messages being sent from and other messages being sent 
to headquarters. 



THE NERVOUS SYSTEM. 237 

13. The cerebrum is the principal seat of intelligence, 
the will, the emotions, sensation, and voluntary motion. 
It would be beyond the scope of this volume to enter into 
a detail of the functions ascribed to the various parts of 
the cerebrum ; but brief mention of the matter will open 
the way to future research, if that is desired. 

14. Ferrier has mapped out areas on the brain, each of 
which, as proven by experiment upon animals, is the seat 
of distinctive nerve-impulses. 1 Examination of the brains 
of various animals appears to have demonstrated that the 
size of the brain and particularly the complexity of the con- 
volutions are proportional to the intelligence of the animal. 
Thus, in the rabbit the cerebrum is small in proportion to 
the brain as a whole, and its surface is smooth. In the 
monkey the cerebrum is proportionately larger, and its sur- 
face is considerably convoluted. In man the cerebrum is 
still larger and more convoluted. 

15. Knowledge of the functions of the cerebrum has 
been partly derived from cases of injury or disease of that 
organ and partly by means of experiments made on the 
lower animals. Thus, when the cerebrum is diseased or 
injured, the power of manifesting mental faculty is more 
or less lost. Will, reason, and memory, one or all, become 
impaired. When the cerebrum of an animal is removed, 
all power of voluntary movement is lost, and the animal 
remains in a state of stupor, retaining, however, the power 
of involuntary or undesigned movement. 

16. The functions of most parts of the brain which lie 
in front of the medulla oblongata are very poorly under- 

1 These areas are called motor centres by some authorities, but exception is taken 
to this term from the fact that the same results may be obtained when the cerebrum 
is removed ; and hence, though the surface shows evidence of being concerned in these 
distinctive functions, other parts are associated with it. 



238 ACADEMIC PHYSIOLOGY. 

stood. " Observation has enabled physiologists to distin- 
guish in the spinal cord and the nerves the portions that 
preside over sensation or over motion ; and the results of 
experiments upon the lower animals make it evident that 
certain regions of the cerebrum are endowed with sensi- 
bility, while others are insensible ; but we have not yet 
been able to recognize in the brain-mass the central organs 
which preside over sensation and over motion." 

17. ... " The brain may be wounded, and even a por- 
tion of it may be destroyed, without any sensible change in 
the intellectual faculties. . . . And, indeed, in the insane, 
science can in many cases prove nothing but their mis- 
fortune, of which no part of the brain suggests, in the 
slightest degree, the cause." Physiology, therefore, is 
very reserved in regard to the functions of the cerebrum, 
and most of the theories concerning them are disputed 
and uncertain. 

18. The Cerebellum. — The cerebellum, or lesser brain, is 
situated in the lower and back part of the skull, under- 
neath the back portion of the cerebrum, with which it is 
connected. It differs materially from the cerebrum in 
structure and in function. It consists of two hemispheres, 
each composed of an external layer of gray matter sur- 
rounding and dipping down deeply into the white, fibrous 
matter. The surface of the cerebellum is also convoluted, 
but in a different manner. The gray and the white mat- 
ter are so interlaced, that, when cut across transversely, 
they present the appearance of a branching tree ; and 
hence the name arbor vita (tree of life) as applied to this 
section of the cerebellum. 

19. Only one of the various functions which physiolo- 
gists have attributed to the cerebellum has been generally 



THE NERVOUS SYSTEM. 



239 



admitted in later times. Its chief office appears to be the 
regulation or co-ordination of muscular movement. When 
an animal has had its cerebellum removed, it can move 
any voluntary muscle at will ; but a confusion in the 




Fig, 46. The Under Surface of the Brain, showing the Origins of the Twelve Pairs of Nerves. 

EXPLANATION. 
A, cerebrum; B, cerebellum; C, medulla oblongata; D, pons Varolii. The Roman 
numerals distinguish certain of the cranial nerves. 

movement is caused, similar to that induced by intoxica- 
cation, the muscles acting irregularly. Thus, voluntary 
movements do not originate in the cerebellum, but only 
the power to produce harmonious action of parts of the 
body. An animal retains sensation when its cerebellum 



24O ACADEMIC PHYSIOLOGY. 

has been destroyed, and both hemispheres may be sliced 
away without causing the slightest pain. 

20. The Pons Varolii. — The pons Varolii (so called from 
the anatomist Varolius, who first described it as a bridge) 
consists of several layers of fibres which pass down from 
the cerebellitm and meet in the middle of the base of the 
brain. It forms a bridge or bond of union between the 
cerebrum and cerebellum above, and the medulla oblongata 
below. 

21. The movements of locomotion are believed to origi- 
nate specially in the pons Varolii, and it has a cross-action 
on the muscles. It is a centre of perception for sensa- 
tions of touch, but it is improbable that it can appreciate 
sensation without the aid of the cerebrum. 

22. The Medulla Oblongata. — The medulla oblongata (Lat., 
oblong marrow) is the name applied to the enlargement 
or bulb of the upper extremity of the spinal cord. It is 
situated within the skull and is continuous with the brain, 
being about an inch in length. Its gray matter occupies 
the interior. 

23. The medulla oblongata acts as an important centre 
for the nerves which regulate the blood-vessels (vaso- 
motor nerves) and the circulation of the blood. It also 
governs those involuntary movements which constitute 
the acts of breathing, swallowing, the secretion of saliva, 
and many others. "When, therefore, it is remembered 
that every impulse passing between the higher parts of 
the brain and every nerve of the body (excepting those of 
sight and smell) must make its way through some portion 
of the medulla oblongata, its importance becomes obvious." 
We see that the vital functions are intimately connected 
with it. When it is injured or destroyed, breathing ceases, 



THE NERVOUS SYSTEM. 24I 

all vital action is suspended, and instant death is the 
result. It also possesses properties similar to those of 
the spinal cord, which will be treated of in the following 
chapter. 



CHAPTER XXV. 

THE SPINAL CORD. THE NERVES. 

1. The Spinal Cord. — The spinal cord is a cylinder of 
nerve matter, continuous with the brain, contained in 
the long cavity of the back-bone. It extends from the 
medulla oblongata downward to about the second vertebra 
of the loins, and is from eighteen to twenty inches in 
length, being nearly as thick as the little finger, and 
weighing about an ounce and a half. It is covered by 
three membranes prolonged from the brain. The second, 
or arachnoid membrane of the cord, unlike that of the 
brain, is not in contact with the pia mater beneath it, but 
forms a loose sac around it. The dura mater, or outer 
membrane, also does not lie close against the inner sur- 
face of the bones of the cavity, but is separated from it 
by a layer of fatty tissue which forms a soft, protecting 
sheath, enabling the column to bend without injury to the 
cord. 1 Like the brain, the cord is divided into right and 
left halves by two deep fissures, one in front and the 
other at the back of the cord, penetrating almost to the 

1 An uninjured piece of the cord may be readily procured from a " loin " of mut- 
ton or from a " sirloin "' of beef. Its general appearance may then be noticed while it 
is still fresh, after which it may be soaked in alcohol till sufficiently hard to be cut 
into sections and the arrangement of its matter noticed. 



242 ACADEMIC PHYSIOLOGY. 

centre. These halves are united by a band of gray mat- 
ter. In the centre of the cord is a very small canal 
which can be seen only with the aid of a microscope. 
The gray nerve-matter of the spinal cord is in the interior, 
and is surrounded by the white matter which forms the 
surface. 

2. Large nerves are given off right and left from the 
spinal cord throughout its length. It is not of equal 
diameter throughout, but has an enlargement in the 
region of the neck and another in the region of the loins. 
These enlargements correspond respectively to the places 
from which the nerves of the upper extremities, and those 
of the lower extremities, originate and pass out through 
openings in the bones. 

3. The spinal cord gives off both motor and sensory 
nerves, and is therefore both a centre of motion and sen- 
sation. It imparts to the nerves of the trunk and limbs 
the power of voluntary* motion. To the heart, the blood- 
vessels, the organs of breathing, etc., it imparts nervous 
force required to sustain their involuntary movements. 
It will thus be seen that the functions of the cord are, in 
part, similar to those of the medulla oblongata, the latter 
transmitting impressions from the cord to the brain, and 
the impulses of the will from the brain to the cord. 

4. Reflex Action. — When the cord is severed (in the 
middle of the back, for instance), the legs and all other 
portions of the body below the point of division become 
insensible, and no effort of the will can make them move; 
all parts above the section, however, retain their sensibil- 
ity and powers of motion. In accidents the cord is fre- 
quently so much injured as to be cut in two in effect, and 
paralysis of the lower part of the body results. Pinching, 



THE NERVOUS SYSTEM. 243 

or otherwise irritating the limbs which are thus discon- 
nected from the brain, causes violent movements of all 
the muscles supplied by nerves given off below the cut, 
and the limbs draw up suddenly by the contraction of 
their muscles ; but this occurs without sensation being 
felt by the brain, and without exercise of the will. Such 
phenomenon is named a reflex action. It consists of an 
irritation or disturbance of sensory fibres which is con- 
ducted by a sensory nerve to a nerve-centre, and a reflec- 
tion of this irritation from the nerve-centre through one 
or more motor nerves causes a contraction of the muscles 
in which these nerves terminate. 

5. The spinal cord is, therefore, not merely a conductor 
of impressions, but it is also a centre for reflex actions. 
This peculiar power is possessed by the gray matter of 
the cord only, the white substance being the conductor 
of impulses. 

6. Numerous reflex actions are occurring continually in 
the body without being recognized by the brain, among 
which are included the actions of organs necessary to life. 
Thus, the action of the muscles employed in breathing is 
the result of reflex action, for in this case the imperfectly 
gerated condition of the blood sent to the lungs produces 
its special irritation of certain sensory nerves ; and the 
impression thus made is conveyed by them to a nerve- 
centre (the medulla oblongata), and from it reflected 
through motor nerves which move the muscles of the ribs, 
the diaphragm, etc., concerned in breathing. 

7. Again, if the substance of the spinal cord is cut 
through on one side only, sensation is destroyed in parts 
below the division on the opposite side of the body, while 
the power of voluntary movement is lost on the same side. 



244 ACADEMIC PHYSIOLOGY. 

Hence, the sensory fibres must cross over immediately on 
entering the cord, while the motor fibres pass down on the 
same side on which they leave the cord. Further, if the 
cord is severed lengthwise into halves, all sensation is de- 
stroyed, while the power of voluntary movement remains 
unaffected. But physiological knowledge of the way in 
which impulses pass up and down the cord is limited, 
and hence very satisfactory statements cannot be made 
regarding them. 

8. The Nerves in General. — The nerve-trunks differ mate- 
rially from the substance of the brain and spinal cord. 
Instead of being soft and pulpy, they are composed of 
tough, thread-like filaments. A number of these fila- 
ments are bound together in a delicate sheath of connec- 
tive tissue ; a number of these small bundles are again 
enclosed in another sheath, and these larger ones again 
unite and are surrounded by an outer sheath to form the 
large trunks. When a large trunk divides, the smaller 
bundles are separated from each other and pass off to 
form nerve-branches. 

9. Sensory and Motor Nerves. — Nerve filaments or fibres 
that conduct impressions of pain, touch, or any other sen- 
sation to nerve-centres are called sensory or afferent fila- 
ments. Those which convey impulses from nerve-centres 
to produce movements of muscles are termed motory or 
efferent filaments. 1 Most of the nerves of the body, 
especially those given off from the spinal cord, consist 
of both sensory and motory fibres, and hence conduct 
impulses in both directions, but not by the same fibres ; 

1 The terms afferent (Lat. ad, to ; and/m>, I carry) and efferent (Lat. e, out ; and 
fero) are probably preferable to sensory and motory, because the irritation of the 
former does not always produce sensation, and the irritation of the latter is not al- 
ways followed by motion. 



^■H 



THE NERVOUS SYSTEM. 24|J 

these are called mixed nerves. Some nerves, as those 
which enable us to see, hear, and smell, consist entirely 
of sensory fibres. 

10. Nerves have no power to generate impulses, but can 
conduct those already produced along their fibres either 
to or from a nerve-centre. Nerve-centres, on the con- 
trary, have the power to produce and to conduct impulses ; 
and they act as receivers and transmitters, as well as gen- 
erators, of impulses. 

11. The nerves are divided into two sets, the cranial and 
the spinal ; the former arising from the brain and passing 
through small openings in the base of the skull, while the 
latter arise from the spinal cord and pass through open- 
ings in the sides of the bones of the spine. Nerves are 
given off in pairs, the nerves of each pair extending in 
opposite directions. 

12. The Cranial Nerves. — Twelve pairs of nerves, suc- 
ceeding one another from before backwards, are given off 
from the brain. Nearly all of these nerves are either di- 
rectly or indirectly traceable to the medulla oblongata, the 
only exceptions being the nerves of sight and of smell. 
" As might be expected from this circumstance alone, the 
medulla oblongata is an extremely important part of the 
cerebro-spinal axis, injury to it giving rise to immediate 
evil consequences of the most serious kind." 

13. The cranial nerves include nerves of the special 
senses, nerves of common sensation, nerves of motion, 
and mixed nerves. The nerves of special sense include 
those that go to the eyes, ears, nose, tongue, and throat, 
and respectively conduct the sensations of sight, hearing, 
smell, and taste. The other cranial nerves conduct sen- 
sory and motory impulses to the muscles of the eyes, face, 



246 



ACADEMIC PHYSIOLOGY. 




Fig. 47. 
EXPLANATION. 
A, A, the cerebrum ; B, B, the cerebellum ; C, C, the union of the fibres of the cerebrum ; 
D, D, the union of the fibres of the two sides of the cerebellum ; E, E, E, the spinal cord; 
1, 1, the cranial nerves ; 2,2, the branches of the spinal nerves that extend to the neck and 
organs of the chest; 3, 3, the branches of the spinal nerves that extend to the arms and 
fingers ; 4, 4, 4, 4, the dorsal nerves that extend to the walls of the chest, back, loins, 
and abdornen ; 5, 5, the lumbar ?ierves that also extend to the chest and abdome?i ; 6, 6, the 
sacral nerves that unite and form the great sciatic nerve of the legs. 



THE NERVOUS SYSTEM. 247 

mouth, throat, stomach, lungs, heart, and other internal 
organs. One pair of the cranial nerves, the pneumo- 
gastric (Gr. pneurna, breath ; and gaster, stomach), a very 
important mixed nerve, sends both sensory and motory 
fibres to the larynx, lungs, oesophagus, stomach, heart, 




Fig. 48. 

EXPLANATION. 

2. the optic nerve, nerve of sight connected with the eyeballs. 

3, the motor oculi, used to move the eyes. 

4, the trochlearis, which rolls the eye downward. 

5. the tri-gemini, whose three branches extend to the upper part of five, face, to the upper 
jaw and teeth, to the lower jaw and teeth (this nerve is affected in toothache), to the tear- 
gland of the eye, and to the nose. 

O, the nerve of the tongue and of taste. 
P, a branch of the nerve of taste, going to the ear. 

Q, the nerve of the teeth of the under jaw, which finally comes out on the chin to supply 
the muscles of expression. 

7, the auditory nerve, being the nerve of hearing. 

and liver. It will thus be seen that any disturbance of 
its branches may cause serious complications of several 
important organs. Each pair of nerves has a name indi- 
cative either of its function, location, or form. 



248 ACADEMIC PHYSIOLOGY. 

14. The Spinal Nerves, — The large nerves that originate 
from the spinal cord and pass off right and left are termed 
spinal nerves. There are thirty-one pairs of these nerves, 
divided into groups according to the regions of the spinal 
cord from which they spring. 1 At the lower end of the 
cord the nerves pass out in the form of a bundle which is 
called the cauda equina (Lat. horse-tail) from its fancied 
resemblance to the tail of a horse. 

15. The nerves in the region of the neck distribute 
themselves to the surface and to the deeper portions of 
the neck, to the outside of the head, to the upper portion 
of the back, to the shoulders, and to the arms ; those of 
the region of the back and of the loins are distributed to 
the muscles of the back and loins, to the walls of the 
chest and abdomen, and to the surface of the legs ; the 
remaining pairs from the lower portion of the cord are 
distributed to the pelvis and to the legs. Several of the 
latter pairs unite and eventually terminate in great trunks 
called the sciatic nerves, 2 the largest in the body, which 
extend to the muscles of the back of the thighs, and 
thence by two smaller trunks to the muscles of the legs 
and feet. 

16. Each spinal nerve arises from two roots, one con- 
sisting of white matter and constituting the motory root, 
and the other of gray matter and forming the sensory root. 
On passing from the cord, these roots become united to 
form a spinal nerve-trunk consisting of sensory and mo- 
tory fibres placed side by side. It follows, therefore, that 

1 There are eight pairs of nerves in the region of the neck, called cervical nerves ; 
twelve pairs in the region of the back, called dorsal nerves ; five pairs in the loins, 
called lumbar nerves ; five pairs in the region of the sacrum, called sacral nerves : 
and one pair at the end of the spine, called coccygeal nerves. 

2 In the distressing disease known as sciatica, these nerves are affected. 



THE NERVOUS SYSTEM. 249 

these nerves are mixed. After division and sub-division, 
they supply fibres to the skin and to the voluntary mus- 
cles generally. In other words, these nerves, by their 
complex ramifications, supply all portions of the body not 
supplied by the cranial nerves. Their divisions are so 
minute and so closely distributed as to make it impossible 
to place the point of a needle on any portion of the body 
without touching a nerve-fibre. 

17. Sensation may be destroyed in any portion of the 
body while that portion still possesses the power of mo- 
tion ; and on the contrary, a portion of the body, a limb 
for example, may be deprived of the power of motion and 
yet retain its sensitiveness to touch, pain, etc. These 
facts early revealed the existence of two orders of nerve- 
fibres, one sensitive and the other motor. Later, and by 
actual experiment, it was demonstrated that their roots 
sprang from distinct portions of the spinal cord. 

18. Experiments made upon living animals have shown, 
(1) that when the trunk of a spinal nerve is irritated, as 
by pinching, applying a hot iron, etc., all the muscles to 
which the nerve is distributed contract, and that pain is 
felt ; (2) that when only the anterior root of the nerve is 
irritated in the same way, the muscles contract, but no 
pain is felt ; (3) that when the posterior root alone is irri- 
tated, there is no contraction of the muscles, but pain is 
evidently felt. Hence it is clear that the power of pro- 
ducing muscular motion is lodged in the fibres of the an- 
terior roots of the nerves, and that the power of conduct- 
ing sensation resides in those of the posterior roots, the 
former being motory and the latter sensory. 

19. In all the experiments mentioned, there is evidence 
that when a nerve is irritated, a something, probably a 



25O ACADEMIC PHYSIOLOGY. 

change in the arrangement of its molecules, is propagated 
along its fibres. If a motor or a sensory nerve be irri- 
tated at any point, contraction in a muscle or sensation in 
the nerve-centres immediately follows. But if the nerve 
be cut, or even tightly tied at any point between the part 
irritated and the muscle or the central organ, the effect 
ceases at once, just as cutting a telegraph wire stops the 
transmission of the electric current or impulse. 1 When a 
limb " goes to sleep," it is commonly because it has been 
subjected to pressure sufficient to impede the circulation 
of the blood, and to obstruct the nervous current in the 
nerves supplied to it. 

20. The incalculable utility and importance to us of hav- 
ing these nerves perform a double function is another 
proof of the surpassing Providence which planned the 
animal structure. The facility and promptness with 
which we are enabled to know that our muscles are con- 
tracting when we wish it, and to estimate exactly the 
amount and direction of the contractions by the aid of 
the so-called muscular sense, allows us to prosecute our 
daily occupation without abstracting the attention of any 
of the other senses from their special operations. This 
" muscular sense " has been recognized by some author- 
ities as a sixth special sense. 

21. The Sympathetic Nervous System. — On each side of 
the spinal column in the upper part of the abdominal cavity 

1 It is an interesting fact that when irritation is applied to that portion of a cut 
spinal nerve which remains in communication with the brain, the pain is not felt at 
the point of irritation, but is always referred to the part in which the nerve naturally 
terminates. The man who has lost an arm or a leg feels pains which he does not refer 
to the stump which remains, but to the hand or foot which he has lost. The irrita- 
tion is transmitted directly to the brain by one or more sensory nerves primarily des- 
tined to these parts, and the brain simply refers the sensation to the extremities of 
the nerve irritated, as though they were still in communication. 



THE NERVOUS SYSTEM. 25 1 

is a large ganglion or collection of nerve-matter connected 
with the brain by a beaded cord. These beads are smaller 
ganglia which act as reservoirs for nerve-force. Nerves 
are distributed from these centres to the heart, lungs, 
stomach, liver, etc. Branches run along the blood-vessels 
also, and from the diverging courses of all the branches 
the name of solar plexus has been given to the central 
ganglia. 

22. In so complex an organization as man, it is very 
difficult, often impossible, to state the points of difference 
in the actions of various parts, and this is especially the 
case in this part of the nervous system. The sympathetic 
system is so called because it is supposed that it estab- 
lishes a sympathy between the various organs of the body. 
Though the functions of the general nervous system and 
the sympathetic are so different, their anatomical union 
and the interlacement of their fibres cause them to react 
upon each other ; but their relations are not thoroughly 
understood. 

23. In all cases of severe shock, the ganglia of the 
sympathetic system are largely involved. When any sin- 
gle organ is diseased or injured, the irritation of the 
branches of the nerves supplied to it causes a sympa- 
thetic action in other organs ; and it thus often happens 
that some unfavorable symptom of one organ is due to a 
diseased condition of one remote from it. 

24. There must be perfect harmony between the two 
nervous systems to maintain health. If the cerebro- 
spinal system is too active, some nerve-force is taken 
away from the sympathetic system, and failure in vital 
processes may result. Again, when the sympathetic sys- 
tem acts too vigorously, nutrition is too active, the grosser 



252 ACADEMIC PHYSIOLOGY. 

part of the living organization predominates, and mental 
activity is held in abeyance. 

25. The sympathetic system is beyond the control of 
the will, and presides over the involuntary movements in 
the processes of nutrition, the circulation, secretion, ex- 
cretion, etc. 

26. Nervous Impulses. — A nervous impulse may be gen- 
erated as follows : An impression made on the skin (as 
for instance by the prick of a needle) causes, by a tear- 
ing of the substance of a nerve-cell, certain changes in 
that cell, and produces what physiologists now call an 
explosion of nerve-force. This explosion causes a move- 
ment along the nerve fibres which is continued until it 
reaches a collection of nervous matter, principally com- 
posed of cells, called a ganglion ; here an increased explo- 
sion is produced, and, at the estimated rate of thirty feet 
per second, the movement is carried on to the brain, which 
recognizes the impression. 

27. How does the brain know it is a needle that is 
pricking ? Only by having been educated to that knowl- 
edge. The infant does not know what hurts it, and it is 
only by repeated impressions that knowledge is obtained. 
The mind, after a time, realizes cause and effect. But 
prior to this education, nature instinctively prompts a 
removal of the cause of pain, and the will sends out along 
the motory nerve fibres that return to the part the man- 
date to remove the offending body. Thus before the 
fullest development of the faculties, an instinctive means 
of protection for organized beings has been provided. 

28. The Mind. — In reply to the inquiry, " What is 
mind?" some one has answered, " No matter;" and to 
that of "What is matter?" has replied, " Never mind!' 



THE NERVOUS SYSTEM. 253 

It is neither desirable nor practicable to enter deeply the 
realms of psychology in this treatise upon the human 
body. 

29. The mind, intellect, or thought is the crowning 
function of the cerebrum, and consists of a number of 
faculties, such as memory, reason, judgment, imagination, 
conception, etc. Just how thought is produced cannot be 
explained. It has been claimed that all mental efforts 
result from a series of explosions that take place in the 
ultimate nerve-cells of the brain. However this may be, 
it is certain that there is as much loss of tissue after 
mental as after muscular effort ; and it is easily demon- 
strated that the material eliminated from the body after 
continued labor of the mind is the product of combustion 
of nervous substance. 



CHAPTER XXVI. 

THE ESSENTIALS OF HEALTHY NERVOUS ACTION. 

1. Primary Requisites. — The healthy action of the ner- 
vous system depends chiefly upon the normal condition of 
other portions of the body and the proper performance 
of functions by its various organs. 

2. It is necessary that the food shall be of a kind that 
can be converted into rich blood. The blood should be 
regularly and equally distributed ; there should be no 
artificial impediment to its circulation. The functions of 
the skin, lungs, kidneys, and bowels should be properly 
performed in order that the waste products may be elimi- 



254 ACADEMIC PHYSIOLOGY. 

nated from the body. A normal amount of bodily heat 
should be maintained. The nerves, especially the large 
nerves of the limbs, should be free from pressure, and 
should be able to convey and receive impressions without 
unnatural stimulation. • 

3. Diseased and disordered functions of an organ pro- 
duce an irritation of the nerve-fibres distributed to it, 
and, by sympathetic action, other nerves participate in 
the irritation, the nervous system becoming more or less 
involved in the disturbance. Hence, it is primarily neces- 
sary to maintain the normal condition of the various 
organs and their functions ; for when these, or any of 
them, are affected, they must be restored to healthy con- 
dition and normal functions, in order to maintain or to 
restore healthy nervous action. 

4. Again, properly regulated work, recreation, and rest 
must be taken into chief consideration in endeavoring to 
maintain nervous vigor. 

5. Mental Work. — The brain and nervous system may 
suffer not alone from over-work. It may be the victim of 
insufficient work. Like the muscles which atrophy or 
waste from disuse, the brain may become weak from want 
of employment and mental food. 

6. Active mental labor, varied by proper muscular exer- 
cise, keeps up a nervous activity that is constantly impart- 
ing renewed vitality to every organ and part of the body, 
and thus tends to prolong life. In a word, it may be 
stated that the most intelligent, and those devoted to 
well-regulated brain-work, live longer, as a rule, than those 
who perform severe physical labor without proper rest 
and recreation. 

7. Regularity tells with marked effect on the physical 



THE NERVOUS SYSTEM. 255 

and mental health in all questions of work, exercise, recre- 
ation, meals, sleep, and rest. Work demands, as a pri- 
mary condition for its perfect performance, regularity of 
its periods. Beyond a certain point, no amount of will- 
power can enable us to continue either mental or physi- 
cal effort. "The experience of every-day life goes against 
giving credit to ' spurts ' of work, and the fable of the 
hare and the tortoise includes a physiological as well as a 
moral application. As a matter of fact, the trades and 
professions in which break-down from overstrain most 
frequently occurs, are not those requiring hard, regular 
application, but those entailing severe temporary strains. 
A laborious occupation may be healthful enough, provided 
the work is performed with regularity. Contrariwise, an 
easy occupation, indulged in under conditions of strain, 
may become thoroughly prejudicial to the health of the 
worker." This can readily be accepted in regard to either 
mental or physical labor, without need of details. 

8. Rest and Sleep. — All severe or protracted mental or 
physical labor is followed by a feeling of weariness or 
exhaustion. This indicates that too great demands have 
been made on the tissues, and that the waste resulting 
from continued activity is becoming greater than the 
supply of nervous force. Work continued under such 
conditions does not produce satisfactory results ; and 
when too severe and protracted may terminate in nervous 
exhaustion. This fact is sufficient to indicate the impor- 
tance of rest at the proper time, in order that the over- 
taxed brain-cells and other parts of the nervous system 
may have opportunity to recuperate. It may be that a 
short period of rest, or the turning of the attention to 
some other mental employment, may provide sufficient 



256 ACADEMIC PHYSIOLOGY. 

relaxation ; or there may be required that complete repose 
that can be obtained only in sleep. 

9. Long continued mental activity produces an increased 
flow of blood to the brain, and necessarily causes a condi- 
tion of wakefulness which is often distressing. Although 
there is a consciousness of mental weariness and a desire 
for repose, the tendency of blood to the brain often con- 
tinues to stimulate it into action, and sleep is either 
disturbed and unrefreshing, or is prevented altogether. 
When the condition of wakefulness becomes chronic, it 
leads to nervous prostration, and the most serious men- 
tal disorder may follow. On the other hand, continued 
muscular effort will always be followed by a desire to 
sleep, from the fact that an extra amount of blood must 
be supplied to the muscles to admit of the increased work. 
Again, after taking food the processes of digestion demand 
that an increased supply of blood should go to the stomach 
and the intestines. In either instance the quantity of 
blood in the brain will be diminished and sleep thus in- 
duced. It is therefore a diminution of circulation in the 
brain that causes sleep, and not sleep that primarily 
diminishes the flow of blood to the brain, as has been 
sometimes claimed. 

10. Insomnia. — In case of insomnia, or sleeplessness, it 
is much better to resort, whenever possible, to some phy- 
siological process that will cause sleep than to take medi- 
cines that will accomplish that result by diminishing the 
frequency of the action of the heart. A brisk half-hour 
walk will often change the flow of blood, divert it from 
the brain, and produce the required rest in sleep ; or an 
equal length of time spent in gymnastic exercises will 
probably prove effective. If muscular exercise fails, a 



THE NERVOUS SYSTEM. 257 

light meal will frequently accomplish the purpose better 
than medicine. 1 Physical labor often exhausts the mus- 
cular and the nervous systems to such an extent that an 
unusual demand for food is created. In this condition of 
exhaustion, sleep is often impossible ; but if nourishment 
is taken, sleep follows promptly. The time-honored idea 
that it is ahvays injurious to take food before going to bed 
is disproved by these facts. If, however, nutriment is 
not required, and no reason for taking food exists, it may 
be harmful ; but it is always better to take a little food be- 
fore retiring than to go to bed hungry. 

11. When digestion is impaired and the liver becomes 
inactive, sleep ceases to be restful and refreshing. A dull 
brain and weakened nerves are the accompaniments in 
such cases. The processes of digestion and nourishment 
must be so improved that the tissue wastes may be re- 
placed before sleep will bring the needed refreshment for 
brain and nerves. 

12. Pure Air. — Fresh air in abundance should be ad- 
mitted to the room during sleep. Impurity of the air 
respired during sleep conduces to impurity of the blood, 
and hence to the injury of the nervous system, which de- 
pends upon the blood for its healthfulness and vigor. 

13. Clothing. — Too much or too little clothing during 
sleep, and at other times, proves injurious to the nervous 
organization by disturbing its functions. The quantity 
of clothing should be just sufficient to afford the required 
aid in the maintenance of the normal temperature of the 
body. 

1 Bathing the face with cold water will sometimes induce sleep, and the coolness of 
a pillow is a well-known inducer of drowsiness — the effects in both instances being 
to diminish circulation of blood in the brain. 



258 ACADEMIC PHYSIOLOGY. 

14. Amount of Sleep Required. — As sleep is a wise pro- 
vision of nature for regulating the waste and supply 
necessary for the continuous development of the forces 
of life, a proper amount of it, at regularly recurring 
periods, is necessary to sustain nervous energy. Many 
brain-workers habituate themselves to live with very little 
sleep taken at irregular periods, a custom which eventually, 
and as a rule, injures the general health. 

15. The amount of sleep required naturally varies with 
the age of the individual. Children, in whom the supply 
must exceed the waste in order to provide for develop- 
ment, require long periods of sleep. Infants, if healthy, 
at first sleep three-fourths of the time; and all children 
under fourteen years of age should sleep not less than 
ten hours. From that age to maturity, all persons will 
undoubtedly be healthier if they sleep long and soundly. 
During the "prime of life," most people require at least 
eight hours sleep. Among many examples of vigorous 
mental and physical life, resulting from regularity of 
work and repose, may be mentioned Alfred the Great 
who divided his day into three parts, devoting eight hours 
to business, eight to study, and eight to sleep and recrea- 
tion. It would, no doubt, be still better to increase the 
number of hours to be devoted to sleep and recreation. 
After middle age less sleep is required, as a rule, because 
bodily activity diminishes, and the same amount of repair 
is not required to build up the tissues. In extreme old 
age the individual demands usually a greater amount of 
sleep ; the bodily powers, becoming weak and easily ex- 
hausted, require more frequent periods of rest. It has 
been estimated that at 4 years of age about 12 hours 
sleep are required ; at 7 years, 1 1 hours ; at 9 years, 10J 



THE NERVOUS SYSTEM. 259 

hours ; at 14 years, 10 hours ; at 17 years, O/J hours ; at 21 
years, 9 hours; at 28 years, 8 hours — the latter amount 
being a fair average for the healthy adult. 

16. Experiment appears to indicate that the soundest 
sleep occurs within the first hour of repose, or soonest 
after the labor or exercise which may have induced it. 

17. The activity of the brain manifested in dreams is 
probably due to the continued wakefulness of certain lower 
centres of the brain, the higher or intellectual centres 
being in a state of repose. Dreams of a remarkable or 
troubled character are usually the result of mental or 
physical over-exertion, or of digestive disturbance. 

18. Narcotic Sleep. — All sleep-producing potions and 
narcotics are absolutely harmful under ordinary circum- 
stances, and should invariably be rejected as such, except 
in serious emergencies under competent medical advice. 
Besides the appalling danger to life to which the deluded 
tippler of morphia and the drinker of chloral are subject, 
the use of these and similar drugs only increases the evils 
of brain or nervous excitement and sleeplessness which 
they are taken to alleviate or prevent. The dose which 
proved effective on the first occasion must be increased to 
produce an equal effect on the second, and so on with each 
repetition. A narcotic habit is developed from which 
there is frequently no escape, and ultimately an irritability 
of the brain and nervous system is produced which is 
fatal to the enjoyment of natural rest. In innumerable 
instances the habitual users of narcotics — opium, lauda- 
num, morphia, chloral, alcohol, etc., have become mental 
and moral wrecks. The saddest results of the use of 
narcotics is the more or less speedy dethronement of the 
will and the moral degradation which follows. 



26o ACADEMIC PHYSIOLOGY. 

19. Alcoholic beverages stimulate circulation in the brain, 
and thus prevent sleep till reaction takes place. Sleep 
that is thus produced is unnatural, and therefore unre- 
freshing. Tea and coffee taken with the evening meal or 
before retiring, produce sufficient brain-stimulus to prevent 
sleep, and they are sometimes taken for this purpose when 
special mental work is to be performed ; but if their use 
in this way is continued, injurious results will follow. It 
is always a safe rule to avoid all beverages in the evening 
that tend to cause a loss of sleep ; and no one who values 
a vigorous brain should consent to employ means of pro- 
ducing a narcotic stupor which, at best, is not nature's 
sweet restorer, balmy sleep. 

20. Rest in Exercise and other Recreation. — Rest does not 
consist in mental and physical inaction alone. Absolute 
inactivity soon becomes irksome and a source of weari- 
ness instead of healthful rest. A change of employment 
in which other faculties of the mind or muscles of the 
body are called into action, while the weary or over- 
strained ones are allowed to recuperate, frequently affords 
precisely the quality of rest needed. 

21. The development of physical as well as mental 
education in schools and colleges, and the attention which 
is being given to means of recreation among all classes of 
society, are beginning to be beneficial to health. Growing 
children and young people are not as capable of great or 
long-continued mental or physical employment as adults, 
and it is essential to health that they should not be kept 
too long at any one kind of work. Physical exercise of a 
well-regulated kind is invaluable in developing the bodily 
powers, and in affording relief from over-taxing mental 
work. It is gratifying to know that means for such exer- 



THE NERVOUS SYSTEM. 26l 

cise are available and being employed by girls and women 
as well as by boys and men. 

22. The great aim and end of exercise, as related to 
rest and recreation, is to provide relief from the duties 
and labors of the day. " The schoolboy's games are the 
antitheses of his school work, just as the walk of the 
merchant, the rowing, bicycling, or gymnastic exercise of 
the sedentary student, form an agreeable contrast to his 
ordinary occupation. It is this feature of alternation of 
occupation, combined with the bringing into play of a 
new set of muscles or thoughts, which constitutes the 
beneficial nature of all recreation. Even the desire for 
alternation which prompts the student of science to amuse 
himself with a novel, is an apt illustration of this truth." 1 

23. Heredity. — Resemblances in the structure and work- 
ings of internal organs of the body are inherited, just as 
resemblances in external form and feature descend in fami- 
lies from parent to child ; and thus it is that tendencies 
toward certain diseases are frequently inherited. This 
inherited tendency is probably most prominent in nervous 
diseases, such as epilepsy, St. Vitus dance, and the various 
forms of insanity. While none of these diseases is neces- 
sarily hereditary, the tendency toward them is common, 
and is greatly increased if a certain disease affects both 
parents. 

24. Under ordinary circumstances, the prospects of 
health in one subject to such hereditary tendency to dis- 
ease would be discouraging. Fortunately, however, just 
as medical experience shows that if a child whose parents 
are consumptive is carefully fed, guarded against cold, 
warmly clothed, caused to breathe fresh air, and kept from 

1 Wilson's " Manual of Health Science." 



262 ACADEMIC PHYSIOLOGY. 

over-strain, he may live to ordinary old age, so may one 
born of parents who are afflicted with nervous disorders or 
insane tendencies. By means of well-directed education 
and restraint, together with careful attention to physical 
health and avoidance of nervous over-strain, similar escape 
may be made from the malady to which he is heir. It will 
thus be seen, that although disease may be inherited and 
"like begets like" as a rule, there is yet a law which, if 
observed, results in modifications of, and departures 
from, the tendency to inherit either mental or physical 
disease-. 

25. Alcoholic Drinks as Related to Nervous Diseases and In- 
sanity. — The primary effects of alcohol, when taken in 
small quantity, is to induce excitement of the brain and 
other nervous centres, causing a temporary stimulation of 
mind and a feeling of brightness and cheerfulness. The 
nerves of the muscles are similarly excited, and, for a short 
time, there is a general feeling of mental and muscular 
vigor. When the quantity is larger, or the small doses are 
more frequently repeated, this initiatory condition is fol- 
lowed by intoxication terminating in reaction whereby 
nerve and muscle become paralyzed, and narcotic depres- 
sion or stupor supervenes. These effects illustrate the 
stimulant and the narcotic action of alcohol. 

26. Alcohol introduced into the body is distributed by 
the circulation of the blood, and comes in contact with 
the brain and other nervous substance. Having a 
strong affinity for water, it absorbs moisture from nerve- 
tissue and paralyzes its action. This effect upon the 
nerve extremities unfits them for their offices to such an 
extent that they become less sensitive to impressions, and 
less capable of carrying impulses and reporting to the 



THE NERVOUS SYSTEM. 263 

brain true external conditions. Thus sight, hearing, taste, 
smell, and touch become dulled and uncertain, and the 
action of the muscles weakened and unreliable. The 
great nervous centres are similarly affected, and are ren- 
dered more or less incapable of performing their controll- 
ing functions. Frequent intoxication, or continual use 
of alcoholic drinks, may produce a degeneration of the 
structure of nervous matter sometimes seen in softening 
of the brain, or in other forms of general paralysis. 

27. While it is true that the effects of alcohol are not 
uniform or equal in different persons, its properties as a 
narcotic are such as to lead generally to the use of gradu- 
ally increasing quantities, and to ultimately induce one or 
all of the effects stated. 

" Whatever affects the character of the nervous tissue 
affects the power to feel and to judge correctly of external 
conditions, together with the power to control the motions 
of the body." Feeling, sensation in general, and mental 
soundness are directly determined by the condition of the 
nervous system. 

28. Aside from the question regarding the exact nature 
of the action of alcohol on nerve substance, it is certain 
that its general effects upon the mind are sooner or later 
as follows : (i) Confused and imperfect perception of sen- 
sation ; (2) the memory becomes less clear and less reten- 
tive ; (3) the imagination is either unrestrained or torpid ; 

(4) the intellect and the power to reason are weakened ; 

(5) the finer sensibilities are blunted, and self-respect is 
more or less lost ; and (6) there is loss of will power and 
self-control. The latter effect constitutes the most seri- 
ous and alarming consequence of the demoralization 
wrought by alcohol on the mind, indicating as it does 



264 ACADEMIC PHYSIOLOGY. 

the establishment of a morbid and ungovernable narcotic 
appetite, an irresistible craving which alcohol or any other 
narcotic tends to create. 

29. The mental defects just stated as due to the action 
of alcohol are closely related to insanity. When the ner- 
vous system is partially paralyzed, the vital processes 
disturbed, and the mind so deranged as to display the 
weakness mentioned as resultant from alcoholic action, 
there is a greatly increased liability to be strongly affected 
by other causes that tend to produce insanity. 

30. That alcoholic intemperance is one of the greatest 
sources of insanity is proven by the statistics of various 
asylums in America and in Europe ; and it is further estab- 
lished by the vital statistics of the past fifty years in the 
United States that the great increase of nervous diseases, 
chief of which is insanity, is directly proportionate to 
the increased use of alcohol and other stimulants and 
narcotics. 

31. Baneful Effects of Opium, Morphia, Chloral, etc. — Severe 
and prolonged attacks of pain, sleeplessness, or nervous 
excitement (especially that which accompanies or follows 
the excessive use of alcohol) frequently lead to the use of 
opium in some of its forms, or of chloral, etc., as a remedy. 
These are powerful and deadly narcotic poisons, and are 
extremely seductive in their first effects. Like all of their 
species, they beget a narcotic appetite which steadily in- 
creases, and stealthily fixes itself upon its victim. The 
habitual use of any of these results in paralysis of nervous 
force, and leads to mental and physical destruction. As 
they are only medicines, they have no safe use other than 
when prescribed by a wise and competent physician, under 
whose directions they may prove blessings, otherwise they 
may prove curses. 



THE NERVOUS SYSTEM. 265 

32. The Use of Alcohol as Related to Crime. — That the action 
of alcohol not only enfeebles the faculties of the mind, 
but also dulls the moral sensibilities, is clearly and pain- 
fully evident in every-day life. Carelessness or indiffer- 
ence as to right and wrong is gradually induced by its free 
use, and a path is thus opened which leads by easy steps 
to dishonesty and to the brutal crimes. 

33. " The tendency of alcohol to paralyze the nervous 
system so that pain is no longer readily perceived, and to 
obscure the more delicate and refining sensibilities of the 
mental part, on the one hand, together with the inflaming 
character of alcoholic beverages upon the animal passions, 
on the other hand, put the individual in the very condition 
that favors evil action. . . . When to the obstructed intel- 
lect and excited baser propensities there is added the seri- 
ous consequences upon the will, as seen in the inability for 
self-control, it seems to follow as a necessity, in the very 
nature of the case, that one who is under alcoholic influ- 
ence would be more disposed to wrong than to right 
action." 

34. The practical illustrations of the effects of alcohol 
in the production and fostering of crime are usually so 
painfully familiar as to require no enumeration here. It 
is a well-known fact that in communities in which alco- 
holic liquors are freely used, riotings, disorder, and crime 
are most abundant. The statistics of prisons everywhere 
show the enormous proportion of cases of crime due to 
alcoholic drink ; and the statement is justified that at least 
three-fourths of all the crime committed is due directly to 
the evil effects of alcohol upon the human mind and body. 1 

1 A few of the many illustrations that may be quoted from the statistics of prisons 
are as follows : Of 14,315 inmates of Massachusetts prisons, 12,396, or 84 per cent, 



266 ACADEMIC PHYSIOLOGY. 

In the crime of murder, the most serious known to the 
law, alcoholic influences have been estimated to apply in 
nine-tenths of the cases. 

35. The Effects of Tobacco. — Tobacco is a brain poison. 
When it is recollected that tobacco deteriorates the blood, 
one-fifth of which constantly flows to the brain, it will be 
understood that the brain and nerves are necessarily 
affected. The effects of so violent a poison as nicotine in 
the blood interferes with the healthful action of the brain, 
and causes nervousness, languor, depression, uneasy sleep, 
and debasement of the intellect, especially in young per- 
sons. Like alcohol and the other narcotics, it begets a 
depraved appetite which the strongest wills often find it 
impossible to withstand, and the gratification of which 
becomes loathsome slavery. The tobacco habit once 
formed becomes a relentless master. 

were reported as intemperate. The County Prison report of Philadelphia for a sin- 
gle year shows that of 13,171 persons committed to prison, 9,038, or 75 per cent, were 
intemperate. In other States and cities the percentage of crime caused by alcoholic 
drink is correspondingly large. In the reform schools for juvenile offenders a very large 
proportion of the boys are from homes in which one or both parents are addicted to 
alcoholic intemperance. 



SUGGESTED POINTS FOR QUESTIONS. 267 



Suggested Points for Questions. 

Chapter XXIV. — 1. Functions of nervous system — motion and sen- 
sation, mysterious force. 2-4. Divisions of nervous system — cerebro- 
spinal, sympathetic, constituents, distribution of nerves, functions of each 
— voluntary and involuntary — connection. 5-7. Nervous tissue — gray, 
white; functions of each; difference of structure — fibrous white, cellular 
gray; texture and amount of each. 8-1 1. The brain — what and where, 
arrangement of substances, seat of nervous force, intellect, etc.; average 
maximum and minimum weight, size compared with brain of lower animals; 
organization and texture govern capacity — comments; coats or membranes — 
location, structure, arrangement relatively, protection, fissure and hemi- 
spheres; divisions of brain. 12-17. The cerebrum — location, relative 
weight, hemispheres, substance arrangement, convolutions, interlacing fibres, 
crossing of fibres and injuries manifested, cross-action of hemispheres, motory 
and sensory impulses — conduction. Cerebrum principal seat of intelligence, 
will, voluntary motion, etc. Areas of distinct nerve-impulses; complexity 
of convolutions and intelligence — illustrations. Knowledge of functions — 
.how obtained, effects of diseased cerebrum, effects of removal of cerebrum. 
Functions poorly understood, portions governing motion and sensation dis- 
tinguished — experiments; central influence not yet recognized. Brain of the 
insane not suggestive, theories disputed. 18, 19. The cerebellum — location, 
unlike cerebrum, hemispheres and relative arrangement of matter, nature of 
convolutions, interlacing of gray and white — arbor vitse. Functions attributed 
to cerebellum — co-ordination; effects of removal of cerebellum in amimls — 
confusion; voluntary movement and the cerebellum — harmonious action; 
painless cutting. 20, 21. The pons varolii — location, structure — bond of 
union; functions — locomotion, a centre of touch. 22, 23. Medulla oblon- 
gata — what and where, gray matter; regulator of circulation, breathing, 
swallowing, etc. — involuntary action; importance as a conductor of im- 
pulses; vital nature — effects of injury. 

Chap. XXV. — 1-3. The spinal cord — location, extent, length, thick- 
ness, etc.; membranes and their arrangement — protecting sheath; right and 
left halves — union; arrangement of matter. Enlargements, spinal nerves — 
pairs; motory and sensory centre — general functions stated as similar in part 
to medulla. 4-7. Reflex action — result of severing spinal cord; effect of 
irritating limbs when disconnected from brain — absence of sensation and 
will. Reflex action defined; spinal cord a centre of reflex action — function 



268 ACADEMIC PHYSIOLOGY. 

of gray matter. Constant occurrence of reflex action — action of vital organs, 
breathing, etc., examples. Effect of severing one side of cord — cross action; 
effect of severing lengthwise on motion and sensation; knowledge limited as 
to movements of impulses. 8. Nerves in general — nature of substance; 
structure — filaments, bundles and sheath, formation of large nerves, separa- 
tion to form branches. 8-n. Sensory and motor nerves — each defined; 
mixed nerves — number and constituents; entirely sensory — examples. 
Power of nerves and of nerve-centres contrasted. Cranial and spinal nerves 

— origin, and passage through bones — pairs. 12, 13. Cranial nerves — 
number of pairs, arrangement; traceable to medulla — exceptions; include 
nerves of special senses, muscles of eye, face, vital organs, etc.; pneumo- 
gastric nerve — branches, functions, effects of disturbance; indicative names. 
14-21. Spinal nerves — what and where; pairs, groups in regions of spine, 
cauda equina; nerves of neck — distribution; of the back; of the loins; 
remaining pairs and distribution; sciatic nerves — nature and distribution. 
Roots of spinal nerves — differences in function; union into trunks, distri- 
bution. Sensation destroyed and motion retained — vice versa — proof of 
two orders of nerves, etc. What experiments on animals have demonstrated 
in irritation of nerve-roots — conduction of motion and sensation by different 
roots. Probable change in arrangement of molecules by irritation; result of 
experiments in irritating, cutting, and tying nerves at different points; a limb 
"asleep" — cause. Utility and importance of double function of nerves — 

— muscular sense. N 21-25. Sympathetic nervous system — location of central 
ganglia — connection with brain; beaded ganglia — distribution of nerves to 
organs; solar plexus. Functions of sympathetic system — anatomical union 
with cerebro-spinal and effect. Sympathetic ganglia involved in shock, 
disease, or injury of an organ — sympathy of action. Necessity of harmony 
between two systems; undue activity or lethargy of either — effects. Sym- 
pathetic system and the will — involuntary action. 26, 27. Nervous impulses 

— generation, explosion of nerve-force, resultant movement, velocity. Edu- 
cation of impressions; instinct of protection prior to education. 28, 29. 
The mind — what? The crowning function of cerebrum; the production of 
thought — theory; combustion of tissue in mental effort. 

Chap. XXVI. — 1-4. Primary requisites of nervous health — normal 
conditions and proper performance of functions of organs. Diseased organs 
and nerve-disorder. Work, recreation, and rest — importance. 5-7. Men- 
tal work — over-work and insufficient work — analogy of effect. Varied 
mental and physical labor — effect. Length of life in mental and in physical 
labor. Regularity important in work, rest, sleep — periodicity. Spurts of 
work and their effects — strains; break-down in severe temporary strains 



SUGGESTED POINTS FOR QUESTIONS. 269 

frequent. 8, 9. Rest and sleep — feeling of weariness indicative after labor; 
unsatisfactory results of fatigued labor — nervous exhaustion; rest at proper 
time important; rest in temporary change of employment; complete repose. 
Mental work and circulation in brain — wakefulness, nervous prostration; 
muscular action diverts blood from brain — result; digestion dimishes circu- 
lation in brain — sleep induced. 10, 11. Insomnia — physiological relief 
best; physical action to divert blood from brain; influence of a light meal; 
exhausted nervous condition as related to sleep — food beneficial ; eating before 
sleep not always harmful. Impaired digestion and sleep — improved con- 
dition essential. 12. Pure air in sleeping-rooms — impure air and the nerves. 
13. Clothing during sleep — too much, too little; disturbance of nervous 
functions. 14-17. Amount of sleep required — regulation of nervous energy ; 
little and irregular sleep — effects. Varying amount at different ages and 
why; Alfred the Great's division of time; less sleep after middle age — reason; 
extreme age and sleep; estimated hours of sleep required for health at dif- 
ferent ages. First hours' sleep soundest. Dreams — probable condition of 
brain, over-exertion, indigestion. 18, 19. Narcotic sleep — potions usually 
harmful; evils of nervous wakefulness increased; increased doses, develop- 
ment of narcotic appetite — irritable nervous system; mental and moral 
wreck; will dethroned, etc. Alcoholic stimulation and reaction — sleep 
unnatural. Wakefulness caused by tea and coffee; vigor of brain and nar- 
cotic sleep. 20-22. Rest in exercise and other recreation — inactivity ceases 
to be restful; change of employment as rest; growing children and long- 
continued mental work; physical relief from mental work. Aim and end of 
exercise in relation to rest — analogies ; alternation of occupation — philosophy 
of. 23, 24. Heredity — tendencies in mental health inherited — increased 
when disease affects both parents. Prospects of health in hereditary tendency; 
means of possible escape— law of modification. 25-30. Alcoholic drink, 
nervous disease, insanity — effect of alcohol on brain and nerve-centres — 
temporary stimulation, intoxication; reactionary effects on nerves and mus- 
cles — depression. Effects on nervous tissue — less sensitive and less capable 
as result; effects on special senses and on great nerve-centres — partial paraly- 
sis; softening of brain. Effects unequal in different persons; increasing use 
induced; judgment and feeling affected. General effects ultimately — per- 
ception, sensation, memory, imagination, intellect and reason, finer sensi- 
bilities, will-power, irresistible narcotic craving. Relation of effects to 
insanity — increased liability. Alcoholism one great source of insanity — 
proof by statistics; increase proportionate to use of narcotics. 31. Baneful 
effects of opium, morphia, chloral — inducement to use; narcotic poisons — 
seductive nature, fixed appetite, paralysis of nervous force, mental and physi- 



270 ACADEMIC PHYSIOLOGY. 

cal destruction; as medicines. 32, 34. Alcohol and crime — dulled moral 
sensibilities — path opened to crime; animal passions inflamed; will and self- 
control enfeebled; free use of alcohol and riotings, disorder, and crime; the 
testimony of prison statistics — the crime of murder. 35. Effects of tobacco 
— a brain poison, nervousness, languor, depression, etc. 



THE SKIN, CLOTHING, AND BATHING. 



CHAPTER XXVII. 

STRUCTURE AND FUNCTIONS OF THE SKIN. 

1. General Importance of the Skin. — The skin is the 
outer covering of the rest of the body, a kind of garment 
or tunic which serves not only to protect the parts within 
and to add beauty to the exterior, but, while serving these 
purposes most admirably, it has other and peculiarly im- 
portant functions. Since the skin is the most extensive 
excretory organ of the body, as well as the principal reg- 
ulator of its temperature, good health depends greatly 
upon the proper performance of its functions. 

2. " Unwonted depression and uneasiness, accompanied 
by loss of appetite and inability to sleep, are prevalent 
causes of complaint among many persons, and these con- 
ditions are commonly attributed to the weather. The re- 
lations which exist between such mental depression as 
constitutes melancholia and the defective discharge of its 
functions by the skin may help to explain the phenom- 
enon." 

3. The connection of cause and effect may not be 

clearly made out ; but the fact remains, that when the skin 

does not act freely, when its functions are seriously im- 

271 



272 ACADEMIC PHYSIOLOGY. 

peded or arrested, melancholy broods over the mind ; and 
just as in the case of melancholia as a disease, the skin be- 
comes dense and inactive. It is not a random conjecture, 
therefore, that cold and damp work their depressing influ- 
ences mainly through the skin. In the interests of health- 
preservation, especial pains need to be taken to secure the 
freest possible action of this great surface of excretory 
glands. Warmer clothing, especially at night, frequent 
ablutions, with sufficient friction, and the promotion of 
skin activity by proper exercise, are obvious measures 
of health which everybody ought to understand and all 
should practise. 

4. To fulfil its complex duties, the skin is composed of 
many parts, all harmoniously united into a single vast 
structure, which, constantly renewed from within, resists 
the agencies which as constantly tend to wear it away 
from without. Elastic and very resistant, it bears, with- 
out being torn, violent shocks and great pressure. In 
short, it at once protects, excretes, purifies, absorbs, and 
is the principal seat of feeling or touch. If in any way 
it is rendered unable in a considerable degree to perform 
its work, death results. 

5. The Layers of the Skin, etc. — On examining the 
skin we find it to consist of two principal layers, an 
outer one called the scarf skin, cuticle, or epidermis (Gr. 
epiy upon, and derma, skin), and an inner layer named the 
true skin, cutis, or derma. These two layers differ in 
structure and functions, but adhere to each other and are 
intimately united with the underlying tissue by fibres 
which mingle with it. The skin of certain portions of the 
body appears to be loose and to slide over the parts be- 
neath, as for instance on the back of the hand, front of 



THE SKIN, CLOTHING, AND BATHING. 273 

the neck, and about the joints: this it does by carrying 
along with it the more or less relaxed tissue. This sup- 
pleness can be most highly valued when the skin is altered 
by disease, as in the condition called " hide-bound," or 
when the affection called eczema has so changed its tex- 
ture that the movements of a joint cause deep and painful 
cracks in the skin. 

6. After enveloping the body, the skin becomes modi- 
fied, and, under the name of mucous membrane, is the deli- 
cate internal skin which lines all the internal cavities ; 
thus, the lining of the mouth, of the inner surface of the 
lips, and of the passages of the nose, is mucous membrane. 
Its structure and functions are closely related to those of 

the outer skin. 

» 

" There's a skin without and a skin within, 
A covering skin and a lining skin ; 
But the skin within is the skin without 
Doubled inwards, and carried completely throughout." 

7. The Derma, or True Skin. — The derma is the thicker 
and tougher of the two chief layers of the skin: it is 
semi-transparent, and is composed of fibres which inter- 
lace so as to form an extremely resistant fabric resem- 
bling felt. The leather of commerce, from the thick, 
coarse sole-leather in which the felt-like fibres can be seen 
with the naked eye, to the softer and pliable calf-skin, and 
the still more delicate kid, is made from the derma, or true 
skin, of animals. 1 

8. The under surface of the derma rests upon loose con- 
nective tissue, which unites it with the flesh or parts be- 
low. It is in this connective tissue that fat is deposited ; 

1 The derma varies in thickness in different parts from a fiftieth to about a sixth of 
an inch, being thickest on the "small of the back." 



274 ACADEMIC PHYSIOLOGY. 

and here water accumulates in dropsy. The upper surface 
is not smooth, but has myriads of little conical or rounded 
elevations, termed papillce (Lat. papilla, a nipple), formed 
by the extremities of nerves and vessels. In certain parts 
of the skin the papillae are scattered irregularly ; while in 
other parts they are arranged in rows, and present the 
appearance of parallel ridges in the surface of the outer 
skin, especially where the sense of touch is very keen, as 
in the tips of the fingers and palms of the hands. The 
epidermis lies in direct contact with the derma : its under 




1 1 



Fig. 49. — Papillce of the Skin from the Palm of the Hand. Magnified 60 diameters. 
The epidermis has been removed. 

surface dips down between ajl the papillae, and is accu- 
rately moulded to fit them. 

9. In the derma are situated nerves, blood-vessels, sweat 
and sebaceous glands, and absorbent vessels, — organs 
whose functions will be noticed later. 

10. The Epidermis, or Scarf Skin, — The epidermis, or cuti- 
cle (Lat. little skin), is a thin, transparent membrane, 
"a sort of organic varnish," designed to come in contact 
with the air and external objects, and to protect the ex- 
quisite sensitiveness of the true skin. Unlike the derma, 
it is not composed of fibres, but of separate roundish cells, 
piled one upon another to a varying thickness in different 



THE SKIN, CLOTHING, AND BATHING. 275 

parts of the layer ; thus, upon the soles of the feet, palms 
of the hands, and wherever friction makes greater protec- 
tion necessary, the epidermis is very thick. 

11. Although the epidermis is in general so thin, it has 
been found to consist of an exterior, horny layer and two 
deeper ones. In the outer, horny layer, the composing 
scales are all flat, hard, and lifeless, only remaining to 
drop off, or to be washed or brushed away. 

12. The middle layer, or rete Malpighii (" net of Malpi- 
ghi "), so named from the anatomist who first described 
it, has round or many-sided, soft, moist cells which grow 
and develop to take the places of those constantly re- 
moved from the horny layer. 

13. The third, or pigmentary layer, lies in contact with 
the true skin. It contains the coloring matter of the skin, 
a black or brownish substance which is more or less 
abundant according to the individual or the race to which 
he belongs, and which contributes to the variety of com- 
plexion seen in people of the same race. If the epidermis 
were removed, the surface of the body would be almost 
blood-red, owing to the many blood-vessels of the derma, 
or true skin. Where the epidermis is thickest, as upon 
the palms and the soles, there is but little red ; but where 
thinnest, as in the lips and cheeks, we have the bright pink 
caused by the blood-vessels of the derma showing through 
the outer skin. 1 

1 " When there are discolored marks on the skin, as in freckles, moth-patches on 
the face, etc., the color deposit takes place in this deeper layer of the epidermis ; 
hence, they are very difficult of removal, because, in order to take away all the coloring 
matter at once, this portion of the skin would have to be removed down to the papillae, 
as in the case of blister. Now, this is painful and troublesome ; and, moreover, expe- 
rience shows that it would be useless to blister off such deformities, because we not 
infrequently see blisters on different portions of the body followed by staining of the 
skin, where no such staining existed previously. We can, however, not infrequently, 



2j6 ACADEMIC PHYSIOLOGY. 

14. The epidermis contains no blood-vessels, but its 
cells draw nourishment from the portions beneath. When 
subjected to much friction or to heat, it puffs up into a 
blister f rom a rapid accumulation of water underneath it; 
and when this outer layer only is removed by slight burns, 
abrasion, or disease, no scar is caused ; but if the derma also 
is injured or destroyed, a scar is formed. In water-blisters, 
"cold-sores," " shingles," and " chicken-pox," the epider- 
mis forms the covering ; and when removed, no matter 
how sore and weeping the surface, if the epidermis alone 
is destroyed, it heals without scars. 

15. Muscles of the Skin. — Certain of the lower animals — 
for instance, the dog, horse, etc. — have a large develop- 
ment of muscle just below and connected with the skin, 
so that they may wrinkle or shake it and thus rid them- 
selves of insects, dust, or moisture. In the human skin 
such muscles are only slightly developed, and are found in 
but few parts ; still it has a certain amount of muscular 
structure connected with its organs or glands. 



CHAPTER XXVIII. 

STRUCTURE AND FUNCTIONS OF THE SKIN {concluded'). 

1. Vessels, Nerves, Glands, etc. — In order to accomplish 
its complex work as a protector, purifier, absorber, regu- 
lator of bodily heat, and custodian of the sensations of 
touch, pain, etc., offices so vitally important to the body, 

by proper stimulants, induce an absorption of the pigment, or produce rapid change 
in the skin, when the new-formed cells will not have the color." — The Skin in 
Health and Disease, by L. Duncan Bulkley, M.D. 



THE SKIN, CLOTHING, AND BATHING. 



277 



the skin has numerous blood-vessels, glands, and nerves, 
each class of which is responsible for the performance of a 
special task. All are as busily employed as are the opera- 
tives in a vast factory. Only when the skin becomes dis- 
eased, or is abused by neglect or 
ill-treatment, do any of its organs 
cease from their labors during 
life. 

2. In the skin the work is car- 
ried on by newes, capillaries, 
sweat -glands, sebaceous glands, 
and absorbent tnbes or lymphatics. 

3. Capillaries. — The true skin, 
or derma, is very abundantly sup- 
plied with blood ; even a fine 
needle cannot enter it without 
drawing blood from one or more 
of the extremely small branches 
of the arteries (the capillaries) 
which spread out in it. The ca- 
pillaries rise into each of the 
little elevations (papillae) of the 
upper part of the true skin, and, 
doubling upon themselves, de- 
scend and become veins which 
ultimately convey the blood back to the heart 
lungs. 

4. Nerves of the Skin. — The nerves of the skin are ex- 
tremely numerous, as we may know from the fact that the 
point of the finest needle on entering the skin is certain 
to find one of them. Certain of the nerves are specially 
sensitive to heat and cold, and give the sensation of pain ; 




llfillil^i^n,:^//^!!! 

Fig. 50. —Section of the Papilla 
of the Shin, showing a Touch Cor- 
puscle. Highly magnified. 

EXPLANATION. 

t, tactile, or touch corpuscle ; d, 
nerve-fibres passing up to it. 



and 



278 ACADEMIC PHYSIOLOGY. 

but a somewhat different class are nerves of touch. This 
latter class enter the papillae of the true skin, and wind 
up into little knots called tactile corpuscles; i.e., "little 
bodies of touch-power," because the sense of touch is sup- 
posed to reside in them. These nerves are found to be 
about one-fourth as numerous as the papillae, being most 
numerous in the finger-tips and palms of the hands, but 
are found in less numbers over most of the body. 

5. The great nerve-supply of the skin is undoubtedly 
for the purpose of protecting the body against injury. 
Endowed with exquisite sensibility, the skin suffers pain 
before the deeper parts can be reached, and thus a danger 
signal is given which often prevents serious or fatal 
results. 

6. The Sebaceous Glands. — The sebaceous (from Lat. 
sebum, fat or tallow) glands, or oil-glands, are minute sacs 
situated in the derma. They vary from T ^o to ^ of an inch 
in diameter in different parts of the skin, and are grouped 
about the deeper ends of tiny tubes or ducts, at the roots 
of the hairs. They secrete and pour out a whitish, oil-like 
substance which, in a healthy condition, is perfectly fluid 
at the temperature of the body. Very few of them open 
directly upon the skin ; almost invariably they are con- 
nected with the hairs, and their ducts empty into the hair 
pits or follicles, from which the sebaceous matter runs out 
along the hair to the surface of the body. Generally there 
are two to each hair, but sometimes large hairs have sev- 
eral around them, forming a kind of collar. 

7. The quantity of matter secreted by the sebaceous 
glands is not very great, and their main function appears 
to be to keep the skin soft and flexible, and to supply a 
natural dressing for the hair. 



THE SKIN, CLOTHING, AND BATHING. 



279 



8. When there is disorder of these glands, and they fail 
to act freely, the skin becomes dry and hard. Sometimes 
the secreted matter thickens and hardens in the ducts, 
forming what are commonly, but 
improperly, called " skin -worms." 
At other times, when the ducts 
are obstructed and the glands go 
on secreting, a swelling, pimple, 
or boil is formed, and inflamma- 
tion continues till the contents 
of the sac burst forth or are lib- 
erated by the prick of a needle. 

9. Surplus sebaceous matter, 
together with the dead scales 
of the epidermis which adhere to 
it, are constantly removed from 
the skin, if it is properly cared 
for; but neglect allows this re- 
fuse matter to accumulate and 
clog the openings of the seba- 
ceous glands and also of the 
sweat-glands, thus throwing their 
excretory work upon other or- 
gans, and causing slow disease. 

10. The Sweat-Glands. — The 
sweat-glands are situated in the 
deepest portion of the true skin, or derma, or in the 
loose connective tissue just beneath it. A sweat-gland 
consists of a little coiled mass or ball of tiny tubing, from 
which a single tube or duct extends upward through the 
entire thickness of the skin and opens upon the surface. 
In passing through the derma, the duct takes a nearly 




Hg. 51. 
EXPLANATION. 

a, a perspiratory tube with its 
gla?id; b, a hair with a muscle 
and two oil-glands ; c, cuticle ; d, 
the papillae; and e, fat-cells. 



28o 



ACADEMIC PHYSIOLOGY. 



direct course ; but through the epidermis it makes a 
number of spiral turns, resembling a cork-screw. 

11. The openings of the ducts are arranged quite regu- 
larly upon the surface, especially on the palms of the 
hands and soles of the feet, where, by aid of a microscope, 
they may be seen in rows between the slight furrows of 
the skin. The tube of each little gland is about ? £o of an 

inch in diameter ; and if it were 
uncoiled and straightened out, it 
would be about 7 V of an inch 
long. Careful computations have 
fixed the total number of the 
sweat-glands at nearly 2,400,000 ; 
and hence their united length 
would be about two and a half 
miles. 

12. In some parts of the skin 
these glands are very numerous ; 
on the palms and soles there are 
about 2,700 in each square inch, 

Fig. 52. -Magnified View of the anc ] on t h e forehead about 1,250 
Epidermis, showing the Pores. 

in equal space. In other parts 
they are. less numerous; the cheeks have but 550 in a 
square inch, while the neck and back have still fewer. 
Surrounding the sweat-glands is a network of capillary 
vessels, and from the blood in these vessels water and 
refuse matter in the form of carbonic acid, fatty acids, 
ammonia salts, etc., are filtered into the glands and cast 
out through their ducts. This water and these impurities 
constitute the sweat, ox perspiration. 

13. Forms and Quantity of Perspiration. — The sweat-glands 
secrete constantly, and under ordinary circumstances the 




THE SKIN, CLOTHING, AND BATHING. 28 1 

sweat is given off in so small an amount that it does not 
collect in drops, but evaporates as soon as it reaches the 
surface. This is called insensible perspiration, because it 
is not perceptible by sight or by touch. It is only when 
the body is exposed to a high temperature or heated by 
exercise that the perspiration manifests itself to sight and 
touch, and becomes what is termed sensible perspiration. 

14. Though the glands are very small, their great num- 
ber gives a vast secreting surface, and their millions of 
ducts pour out fluid nearly equal in quantity to that sent 
out by the kidneys. The amount of perspiration within 
a given time varies according to the temperature and 
moisture or dryness of the air, amount of exercise, quan- 
tity and quality of food and drink, etc. Results of care- 
ful experiments agree, however, in placing the daily per- 
spiration in the average person in good health at two 
pounds, or two pints ; and yet half of this quantity may 
be shed in a ^single hour of vigorous exercise or of ex- 
posure to a high temperature. Excessive perspiration is 
followed by great thirst, the blood demanding water to 
take the place of that which it loses. 

15. Absorption through the Skin. — The skin has the prop- 
erty or function of absorbing various substances applied 
to its surface, and absorption takes place most readily in 
those parts where the outer or horny layer of the epider- 
mis is thinnest. Medicines are sometimes administered, 
and produce their effects upon the system, by being 
rubbed into the skin. Thirst is considerably relieved by 
a bath, and it is even possible to supply nourishment by 
absorption through the skin. Children, when' so much 
exhausted by disease as to be unable to eat, or whose 
stomachs refused to retain food, have been saved from 



282 ACADEMIC PHYSIOLOGY. 

starvation by rubbing nourishing substances upon the 
surface of the body. In all these instances, particles 
absorbed pass into the blood. 

16. Respiration or Breathing through the Skin. — It may be 
surprising that we breathe through the skin ; yet a cer- 
tain amount of what might be called respiration goes on 
through it. Experiment has shown that the skin absorbs 
oxygen and gives off carbonic acid. In an experiment 
made by Aubert, a person was enclosed in an air-tight 
case, leaving only the head exposed. By proper appliances 
the enclosed air was tested and found to contain less oxy- 
gen, while it had gained .05 per cent as much carbonic 
acid as was given off by the lungs in an equal time, thus 
proving that these gases are interchanged not only by the 
lungs, but through the skin also. 

17. Functions of the Skin, Lungs, and Kidneys compared. — 
The functions of the skin are, therefore, similar to those 
of both lungs and kidneys. Like the lungs, the skin 
absorbs oxygen and gives off carbonic acid, water, etc. ; 
and like the kidneys, it excretes both water and saline 
matter. The skin is, however, more closely related to the 
kidneys than to the lungs ; and in hot weather, when the 
excretion by the skin increases, that of the kidneys dimin- 
ishes — the reverse being true in cold weather. 

18. When the free action of any one of these organs is 
interrupted, there is usually a tendency to throw its work 
upon the others ; but this mutual aid goes only a little 
way without serious results to health. If, for instance, 
the kidneys become unable to perform their work, death 
results, no matter how active the skin may be ; and on 
the other hand, if the skin were coated with an impene- 
trable varnish, death would soon follow, even though the 



THE SKIN, CLOTHING, AND BATHING. 283 

lungs and kidneys continue their work. 1 It is not uncom- 
mon that burns or scalds which destroy large portions of 
the skin, though not injuring deeper parts, result fatally. 
The importance, therefore, of taking proper care of the 
skin can hardly be overestimated, since neglect may re- 
sult in clogging the many pores through which a vast 
amount of fluid and waste matter passes out of the system. 



CHAPTER XXIX. 

REGULATIVE AGENCY OF PERSPIRATION. 

1. Perspiration and Heat. — Besides its work in casting 
out waste and impure matter from the blood, etc., the 
skin has an important function to perform in aiding to 
maintain a uniform temperature in the body. Thus 
while heat is constantly being generated in the body, the 
skin is radiating, or giving it off, at the surface. By a 
proper balance of these two .processes, the temperature of 
the interior of the body in health is kept uniformly at about 
98^° Fahrenheit, though the standard varies %° or i° 
with the time of day or night and with the sleeping or 
waking state. 2 

1 When animals have the hair shaved off and the skin completely covered with an 
impenetrable coating, as by varnishing the surface, death always takes place ; and the 
story is current among physiologists that at the coronation of Pope Leo X. (1475— 
1521), a little boy was covered with gold-foil, or gilded, to represent a cherub. He 
became ill almost immediately, however, and died in a few hours after the ceremonies, 
because the gold-leaf and varnish prevented the action of the skin. 

2 On the surface some parts are, of course, cooler than others according to the 
exposure to the air in contact with them. The average normal temperature of the 
surface is about 98^°, and is ascertained usually by placing the bulb of a thermome- 
ter in the arm-pit. 



284 ACADEMIC PHYSIOLOGY. 

2. When the body becomes heated by exercise or by 
exposure to hot air, the vaso-motor, or vessel-moving 
nerves, which control the muscular coats of the blood- 
vessels, become affected and allow the capillaries of the 
skin to expand, thus inducing an increased flow of blood 
into them. This increase of blood in the capillaries 
causes the sweat-glands connected with them to act or 
secrete more rapidly, and to immediately pour out an 
increased quantity of warm perspiration from the blood. 
Evaporating from the surface and giving place to more 
from the interior, the perspiration abstracts heat and 
keeps the temperature of the blood at its proper degree. 
The greater the quantity of water thus evaporated the 
lower the temperature of the body would be if the heat- 
making process within was not going on at the same time. 

3. Perspiration and Cold. — Cold, on the contrary, acts upon 
the vaso-motor nerves in such a manner that they over- 
stimulate the muscular coats of the small blood-vessels of 
the skin and cause them to contract, and thus diminish 
the size of the vessels. The blood is not only driven out 
of the blood-vessels in this way, but the ingress of new 
blood is prevented ; and, consequently, the sweat-glands 
having less blood in contact with them, secrete and send 
out perspiration much more slowly. Evaporation from 
the skin being thus diminished, the radiation or loss of 
heat is correspondingly lessened. 1 

4. We readily " catch cold " when this vast evaporating 
surface is exposed to a sudden lowering of temperature 
in a draught of air, or when too thinly clad. As a learned 

1 When the blood at the surface of the body, that is, in the skin, has become cool 
at a rate too rapid to be compensated by the production of heat in the interior of the 
body, death from freezing occurs. 



THE SKIN, CLOTHING, AND BATHING. 285 

physician has pithily remarked, " Of course, as this blood 
which is driven away from the surface must have some 
place to go to, it flows inwards to the warm parts of the 
body, filling them too full of blood, or, as it is called, 
congesting one or more of the vital organs. Whichever of 
these happens to be our ' weak spot ' is, of course, least 
apt to recover promptly from the temporary congestion, 
and the most liable to become the seat of serious inflam- 
mation. If, for example, a man's lungs are his weak 
point, inflammation of the lungs, called pneumonia, run- 
ning on, if neglected, to consumption, may be the result, 
etc." Other results may be pleurisy, bronchitis, rheuma- 
tism, bowel and kidney trouble, with their dangerous or 
fatal effects, all resulting from sudden chill and checking 
of perspiration. 

5. When the bodily temperature is lowered, say to 
eighty degrees, death occurs as by freezing. 

6. Perspiration and Dry Air. — When air is warm and dry, 
it is in condition to absorb much moisture, and hence per- 
spiration evaporates very rapidly into it. For this reason, 
a man perspiring freely may remain without injury for a 
considerable length of time in an oven where meat could 
be cooked. It is related that the workmen of the sculptor, 
Chantry, were accustomed to enter a furnace in which 
the temperature stood at 350 ; and that Chabert, a public 
performer who styled himself the " Fire King," remained 
in an oven heated to 6oo° while a*beefsteak was cooked 
beside him ! Men employed in iron-working establish- 
ments, for instance at " puddling" furnaces where the 
heat is intense, sprinkle themselves with water, and thus 
add moisture to be evaporated from the skin. In all 
these instances, the dry heat of the air is expended in 



286 ACADEMIC PHYSIOLOGY. 

changing the abundant perspiration or water into vapor, 
and the temperature of the blood is but slightly raised. 

7. Perspiration and Moist Air. — Very moist air, on the 
contrary, already contains so much watery vapor that it is 
unable to absorb much more — sometimes none at all — 
and at a high temperature it causes great physical discom- 
fort. The perspiration pours out upon the skin, but re- 
mains there unevaporated and fails to cool the body. A 
temperature of 8o° on a "damp day " may, therefore, cause 
more discomfort than 90 causes when the air is dry. 
Thus it is that men endure the intense dry heat about 
puddling and smelting furnaces, but cannot as easily bear 
a lower temperature in the moister open air of a hot 
day. Exposure to a moist atmosphere at a high tempera- 
ture, especially if vigorous exercise is being taken, is apt 
to cause what is called " sun-stroke," or " heat-stroke," in 
which case the temperature of the blood mounts to about 
1 1 3 , and quickly proves fatal unless relieved by cold. 

8. The Hair. — The hair, as well as the nails, may be 
regarded as an appendage of the epidermis, so changed in 
structure as to fulfil special offices. A hair consists of 
two parts, the root and the exposed part, or shaft. The 
root is somewhat pear-shaped, and is situated in a little 
pit or sac, called a follicle, deep in the derma, or true skin. 
At the bottom of each pit is a little projection, or hair 
papilla, which extends into the root of the hair, and from 
it come the materials for the growth of the hair, there 
being a minute blood-vessel in its interior. Even when 
"plucked out by the roots," hair will be reproduced if the 
little papillae are not destroyed, and remain in a healthy 
state ; and therefore superfluous hair can be kept from 
growing only by destroying the life of the hair papillae. 



THE SKIN, CLOTHING, AND BATHING. 287 

9. Through the centre of each hair, from end to end, 
runs a canal filled with cells which contain the coloring 
matter of the hair. In diameter, hairs vary from j^ to 
jls of an inch on different parts of the body, the average 
diameter being about 4^ of an inch. Dark hair is usually 
coarser than light hair, and flaxen hair more abundant 
than darker shades. It has been estimated that the num- 
ber of hairs on the average head is about 120,000. Few, 
if any, hairs are round, and they are so elastic as to 
stretch nearly one-third of their length. The substance 
of hair is very enduring. 1 

10. The hair is useful in various ways : that on the 
head protects it from extremes of heat and cold, and the 
eye-lashes and hairs of the nose and ears protect those 
organs from dust, insects, etc. 

11. The Nails. — The nails are composed, much like the 
epidermis, of hard, horny matter arranged in cells. They 
lie upon a bed or matrix (from Lat. mater, mother), just 
as the scarf-skin rests upon the true skin. They grow in 
length by constant addition of cells at the root, and thus 
push forward over the matrix. Cells are deposited on the 
under surface of the nails by the matrix, causing them to 
be thicker at their forward ends than they are at the 
roots. 

12. An injury to the matrix, or bed of the nail, such as 
from splinters driven under the nail, or even from severe 
bruises, need not cause a disfigured nail except at the 
immediate point of injury; but injury or disease at the 
root generally causes distortion of the nail. Certain dis- 

1 A remarkable illustration of the enduring character of human hair may be seen 
in the British Museum, where has been placed a wig, lately found in a temple at 
Thebes, which is supposed to have been worn by an Egyptian priest at a period not 
less than 3,400 years ago. 



288 ACADEMIC PHYSIOLOGY. 

eases of the skin extending to the back of the fingers 
sometimes involve the roots of the nails, and cause ill- 
growth. The growth of the nails is often arrested by 
sickness which interferes with the deposit of nail-making 
material, and the portion of a nail grown during sickness 
is often perceptibly thinner than that which is formed 
during health. Nails themselves are subject to diseases ; 
and as age advances, they gradually become harder and 
brittle. 

13. The use of the nails is to protect the sensitive 
finger-tips, and, by serving as a firm backing, aid the 
sense of touch in them and assist in picking up minute 
objects. They also preserve the symmetry of the fingers ; 
for, when the nails are kept too closely trimmed, the 
fingers are apt to become " club-ended." 



CHAPTER XXX. 

CARE OF THE SKIN. BATHING. 

1. Hygiene of the Skin. — The hygiene of the skin re- 
quires a consideration of two chief questions : 1st, how, 
in caring for the skin, to cleanse it from impurities ; and 
2d, how to assist it in regulating the temperature of the 
body ; the former by proper bathing, the latter by proper 
clothing. 

2. Cleansing of the Skin Necessary. — The millions of " pores " 
of the sweat and sebaceous glands pour out a great quan- 
tity of matter, some of which, becoming mixed with the 
loose, bran-like scales of the scarf-skin, dries and remains 



THE SKIN, CLOTHING, AND BATHING. 289 

fastened to the surface of the skin, clogging the mouths 
of the pores and interfering with the action of the glands. 
A laboring man perspires freely, his flannel shirt chafes 
his skin, and thus removes much of the matter deposited 
upon it ; but a person of less active muscular employ- 
ment, or one who lives a sedentary life in warm rooms, 
is accumulating upon his skin a dangerous form of matter 
brougJit to it for removal. 

3. Poisonous matter left upon the skin may be absorbed 
into the blood and cause disease. Careless painters, 
mirror-silverers, and workmen in lead factories are fre- 
quently poisoned by lead or by mercury absorbed through 
the skin. 

4. It has been well-said : " If the vital fluid, the blood, 
becomes impure and stagnant from a burden of waste 
matter which should, but cannot, escape from the skin, or 
which has been carried there to be discharged only to find 
the outer door shut, and then has become absorbed by the 
scavengers of the body, is it surprising that the individual 
feels depressed and inactive, and that he has a poor appe- 
tite and aching head ? " 

5. It will be readily understood, therefore, that in order 
to have a healthy skin or a healthy body, to escape lassi- 
tude, headache, and feverishness, the skin must be kept 
clean and free from all accumulations. It has been said 
that " cleanliness is next to godliness." 

6. A Warm Bath for Cleanliness. — For purposes of clean- 
liness, warm baths — those in which the temperature of 
the water is from jo° to 8o° — are the best. Water of this 
degree of heat usually gives an agreeable sensation of 
warmth, avoiding the shock of a cold bath (one below 6o°) 
and the excessive stimulation of a hot bath (one of 85 



29O ACADEMIC PHYSIOLOGY. 

and upwards). It is well to recollect that a warm bath is 
all sufficient for cleanliness, and is not a hot bath : the 
latter should be reserved for cases of great fatigue, the 
first stages of a cold, etc. 

7. Care should be taken not to remain too long in a warm 
bath, as such a practice has a very weakening effect when 
often indulged. As a general rule, ten to fifteen minutes 
are long enough for a warm bath. 

8. The ski ? 1 should be perfectly dried by friction with 
towels or with bath-mittens on emerging from a warm 
bath, because, as it is full of blood and in a relaxed condi- 
tion, exposure to cold air, or even to drafts of warm air, 
is dangerous. 

9. The frequency with which a bath should be taken 
varies considerably with the person. Some whose skins 
send out very large quantities of strong-smelling perspira- 
tion may require a bath daily, or even twice daily, in warm 
weather. It is a safe rule in health, to which there are 
exceptions of course, to bathe the whole body twice a week 
in winter, and every other day in summer. The frequency 
may be increased gradually to three times a week in win- 
ter, and to a daily bath in summer. While bathing may 
be carried to an injurious excess, it is certain that the 
majority err in the opposite direction. 

10. The best time for taking a warm bath, for those who 
easily take cold, is at night, just before retiring. Going 
to bed at once, they avoid exposure for a number of hours 
after the bath. Unless a person can stay in-doors several 
hours after taking a warm bath, it should never be taken 
in winter before the bed-hour. 

11. Baths should never be taken immediately after a meal, 
as the change in the circulation of the blood caused by a 



THE SKIN, CLOTHING, AND BATHING. 29I 

changed temperature of the surface of the body interrupts 
the work of the digestive organs ; thus, for instance, if 
the blood is attracted to the surface of the body in large 
quantities, the temperature of the stomach will be some- 
what lowered and its work will be delayed. At least three 
hours should elapse after a meal before a bath is taken. 

12. Soap is necessary to remove the fatty matter poured 
out by the oil-gla7ids. However, the soap used in bathing 
should not be too strong, — that is, should not contain too 
much alkali. There are very great differences in soaps 
and in their effects upon the skin. The common yellow 
bar soap and ordinary soft soap are stimulating and very 
irritating to tender skins, and are apt to remove the oil of 
the skin so effectually as to leave it dry and roughened ; 
but old, white Castile soap, made from olive oil and soda, 
and some of the best toilet soaps, have little, if any, bad 
effect, while they serve to cleanse the skin. 

13. The cheap scented and colored soaps often have 
clays, etc., mixed with them to increase the bulk and 
cheapen the cost, and are too frequently scented, colored, 
and gotten up showily for the purpose of disguising the 
impure and irritating material which they contain. Cheap 
soaps are often made from poor oil or fat, and have been 
known to contain bits of bone, decaying matter, and even 
pus globules : such soaps have caused skin diseases and 
eruptions on the face when used in shaving. Too much 
care cannot be taken in selecting a toilet soap, as a " cheap " 
one may prove to be a very dear one. 

14. Hot Baths. — Hot baths are very stimulating to the 
skin, and are of excellent service in case of great weariness. 
They are also an effective means of breaking up a cold in 
its first stages ; that is, when the skin first becomes chilly 



292 ACADEMIC PHYSIOLOGY. 

and " sore to the touch." After a hot bath of two minutes, 
the skin should be rubbed thoroughly dry — care being 
taken to prevent its exposure to cold air or to drafts of 
any kind — and the person should retire to bed immedi- 
ately. The hot bath, a drink of hot lemonade or even of 
cold water, and wrapping the body in a warm blanket in 
bed, will be quite certain to make the glands active, open 
the pores, and drive out the cold with the perspiration. 
But hot baths are much less safe for ordinary bathing 
than those of a more moderate temperature ; because when 
frequently employed they are weakening, and the liability 
to take cold afterwards is very great. 

15. Cold Baths. — The first effect of cold Water brought 
into contact with the skin is the same as that of cold air, 
or of any other cold when applied to it. The nerves re- 
ceive a shock which causes a contraction of the blood- 
vessels of the skin, and the blood is driven toward the 
interior of the body, and the lungs and heart are stimu- 
lated to increased action. If the heart is vigorous, it soon 
sends the blood rebounding to the surface ; and by this 
reaction the skin becomes rosy and a pleasurable warmth 
is felt. While this glow continues the bath should end, else 
a feeling of weakness and depression will follow, and may 
last during a number of hours or an entire day. To in- 
crease the glow and the good effects of the bath, the skin 
should be rubbed briskly with towels or with bath-mittens. 

16. If reaction does not set in promptly, the effects of a 
cold bath are evil. When the heart is not vigorous, the 
bath may fail to stimulate its action enough to drive the 
blood back toward the surface. In this case, the blood 
over-crowds various internal organs, and, by remaining too 
long in them without proper circulation, becomes stagnant 



THE SKIN, CLOTHING, AND BATHING. 293 

and impure. Thus, from over-fulness of blood the brain 
may become dull and confused, the lungs oppressed, the 
stomach nauseated, and the liver interrupted in its work. 
If the cold bath be taken at a proper time and in a proper 
manner, and reaction still fails to take place promptly, the 
bather may conclude that a cold bath injures him. 

17. Sea-Bathing. — Salt-water baths are more stimulating 
than fresh-water baths, and, when properly taken, are one 
of the best means of strengthening the system. In cases 
of weakness from rapid growth in young people, the sea- 
bath is almost always of great benefit. Persons of very 
nervous temperament, and those who suffer from any acute 
disease, as, for instance, disease of the valves of the heart, 
should be very cautious in resorting to cold- or sea-baths ; 
in fact, all invalids will find it much safer to take compe- 
tent medical advice, and obtain explicit directions as to 
when, how long, and how often to bathe, if at all. 

18. In taking a surf-bath, it is best to run or walk rap- 
idly into the water, and dip the whole body, head included ; 
or to allow a wave to dash over and wet the entire person 
at once.. One should be comfortably warm on entering the 
water, and should exercise actively while taking the bath, 
thus causing the temporary chill to give place to a glow 
which may be increased by thorough rubbing. The first 
shock is usually followed by a return of warmth which 
continues for a time and is again followed by chilliness. 
This second chilliness is a danger-signal, and the person 
should leave the bath instantly ; but better still, leave it 
before the second chill begins. Many persons who are 
not strong enough to endure the shock of a surf-bath find 
a cold "still-bath," or a bath in warm salt water, both 
agreeable and beneficial 



294 ACADEMIC PHYSIOLOGY. 

19. Robust people may bathe twice a day in the sea 
without harm ; but for most persons a bath once a day is 
sufficient. For reasons already given, a bath should never 
be taken soon after a meal ; and thorough drying and fric- 
tion of the skin is as necessary after a sea-bath as in other 
bathing. In order that the good effects of sea-bathing 
shall not be counteracted, it must be recollected that care 
in diet and in other hygienic matters is as necessary at 
the seashore as elsewhere. 

20. Friction Baths. — In the morning, before breakfast, 
the body is least able to react from the chill of the ordi- 
nary cold bath. Many hours elapse between the time of 
the evening meal and breakfast, and meanwhile the fires 
of the body burn low from lack of fuel (food) ; the " river 
of life " flows sluggishly, and the system is not in a condi- 
tion to meet best the effects of a full bath, either cold or 
warm. 

21. A wet friction batJi, however, may be taken before 
breakfast, even in winter, without endangering health. 
Such bath may be taken in the following way : " Procure 
a pair of mittens of hair, crash, or any rough, coarse ma- 
terial. Wring them out in cool water, and rub trunk and 
limbs quickly, but not violently. There should not be a 
drop of water visible on the skin. Wipe off the moisture 
with a soft towel, and repeat the rubbing with dry hands." 
This bath is highly beneficial except, probably, to actual 
invalids, and produces a glow and a delightful feeling of 
stimulation. 

22. A dry friction bath is simply an air bath in which 
friction of the skin is employed, and it may be taken as 
follows : Remove the clothing, expose the body to the air, 
and use the dry mittens as in the wet friction bath. The 



THE SKIN, CLOTHING, AND BATHING. 295 

roughness of the mittens may be increased by saturating 
them with a strong solution of salt and water, and then 
drying them to be ready for use. 

23. Friction of the skin while it is exposed to the air has 
a tonic effect ; and either the wet or the dry friction bath 
has a beneficial effect on the wearied body or jaded brain. 
When taken at night, a friction bath is sleep-producing, 
for it calls away the over-plus blood from the brain, and 
relieves it from pressure which is a common cause of rest- 
less wakefulness. 

24. Washing of Face and Hands. — Cosmetics. — The skin of 
the face and hands is washed or bathed more frequently 
than that of other portions of the body ; and if strong soap 
is used often, the natural oil will be removed so completely 
as to make the skin too dry, and call for the application of 
grease, vaseline, etc. It is best to use soap only when 
necessary to remove impurities that refuse to yield to 
water alone. In winter, particularly, the skin of the face 
and hands should be perfectly dried after washing before 
exposure to cold air ; for a sudden contraction of moist 
skin by exposure to cold air cracks the outer layer, and 
these cracks extending to the true skin become very 
painful. 

25. Cosmetics and powders for the skin frequently con- 
tain poisonous ingredients, such as large quantities of lead, 
and many of them are known to be injurious to the skin 
and to cause disease : they should be avoided as a class, 
no matter how seductive their advertisement. As their 
composition is commonly unknown, those who value health 
and beauty of complexion should not. allow themselves to 
be tempted to try them. If, as is sometimes the case, the 
skin of the face is very greasy, pure rice-powder or a little 



296 ACADEMIC PHYSIOLOGY. 

calcined magnesia will absorb the oily matter and be quite 
harmless. Daily moderate friction of the face with a 
towel aids greatly in keeping open the ducts of the seba- 
ceous glands, and does much to prevent the formation of 
black specks (" skin-worms ") and red blotches so common 
on the faces of young persons. 

26. The most effective beautifiers of the skin are judi- 
cious washing or bathing, pure air and exercise, a careful 
diet, 1 and avoidance of alcohol and tobacco. 

27. Care of the Scalp. — Hair-Dyes. — The scalp should 
be kept clean and its pores unobstructed. Here, as else- 
where, the scarf-skin is being shed constantly ; and if its 
scales are allowed to remain and combine with drying seba- 
ceous matter, they constitute what is called " dandruff.'' 
Sometimes an unhealthy secretion of the sebaceous glands 
is seen as a greasy coating upon the scalp, or in the form 
of yellowish, greasy scales. While dandruff does not "eat 
off the hair," the conditions that tend to produce it should 
never be neglected, because they are attended, sooner or 
later, with baldness. The hair and scalp should receive a 
daily brushing with a comparatively soft brush. A fine- 
toothed comb, while giving temporary relief from dan- 
druff, will irritate the skin and aggravate the difficulty. 
The scalp should be washed occasionally. An ointment 
composed of castor-oil, alcohol, and a small quantity of oil 
of rosemary, is a valuable remedy in case of dandruff : it 
should be well rubbed into the scalp. 

28. Hair-dyes which are represented as containing no 
poisonous mineral matter, often depend upon salts of lead 
or nitrate of silver for their efficiency in dyeing. These 

1 Indigestion from overeating, highly-seasoned food, and excess in drink, often 
cause eruptions of the skin. 



THE SKIN, CLOTHING, AND BATHING. 297 

harmful minerals are absorbed through the skin when fre- 
quently applied to the hair of the head or to the whiskers, 
and they sometimes produce dangerous or even fatal results. 
Cases of paralysis apparently due to the use of hair-dye 
have been reported ; and it is said that Bright's disease of 
the kidneys may occasionally owe its origin to a long-con- 
tinued use of skin-powders and hair-dyes. 

29. Alcohol and the Skin. — Bodily Temperature, etc. — The 
primary effect of a considerable quantity of alcohol taken 
into the system is a paralysis of nerve extremities, and for 
a time it suspends the power to feel. The sense of touch, 
also, frequently becomes much less delicate in habitual 
drinkers. 

30. The nerves of the small blood-vessels of the skin 
becoming paralyzed, these little tubes relax and become 
over-crowded with blood, as is shown by the flushed face, 
hands, and skin generally. The temperature of the sur- 
face is at first increased ; but the flow of a greater quan- 
tity of perspiration and its rapid evaporation, together 
with the enlarged radiating surface of the blood-vessels, 
soon aid to lower the temperature much below the standard 
of health. Hence, alcohol is, in the end, a reducer instead 
of a producer of warmth, and the power of resistance to 
cold is weakened by its action. It is especially dangerous 
to persons who drink it when they are to be exposed to a 
low temperature. 1 

Sometimes the over-filled condition of the capillaries of 
the skin becomes permanent and is manifested in the red, 
blotched face and nose of the " heavy drinker," a condi- 

1 It is the testimony of all Arctic explorers that men who do not use alcohol 
endure exposure to severe cold much better than those who drink it ; in fact, it has 
been found necessary to avoid its use when about to be exposed to severe cold for a 
considerable time. 



298 ACADEMIC PHYSIOLOGY. 

tion so remarkable as to amount to disfigurement of the 
skin. 

31. Tobacco and the Skin. — Through its effects on the sys- 
tem in general, the excessive use of tobacco interferes with 
the health of the skin. It is not unusual to find the skin 
of inveterate smokers either pale or of a yellowish, smoky 
cast. When a boy " takes to smoking," his skin is apt to 
become pale and unhealthy. 

32. Chronic Diseases of the Skin. — In concluding a treatise 
upon the skin in health and disease, Dr. L. B. Bulkley 
says : "In chronic skin diseases the whole system is chroni- 
cally deranged ; and to accomplish their cure, and to pre- 
vent their return, it is frequently necessary to alter the 
condition of the system. To accomplish this, we cannot 
simply apply a wash or a salve, or take a few drops of this 
or that remedy, but must by a combination of all the 
means known to science, by diet, hygiene, and medicine, 
restore the disordered organ and system to the state of 
health. And the application of the same rules, together 
with self-restraint, will serve to prevent a recurrence of 
the skin disease." 1 



CHAPTER XXXI. 

CLOTHING. 

1. Object of Clothing. — From moral and ornamental stand- 
points, clothing generally receives much attention and 
consideration ; but its main purpose, the preservation of 
health, is too frequently ignored. It will be recollected 

1 The Skin in Health and Disease (Health Manuals, vol. iii.), by L. Duncan 
Bulkley, M.D., Attending Physician for Skin Diseases, etc., at the N. Y. Hospital. 



THE SKIN, CLOTHING, AND BATHING. 299 

that external portions of the body are from one to two 
degrees cooler than internal parts, and that radiation and 
evaporation from the surface constantly tend to increase 
this difference. Any considerable deviation from the nor- 
mal standard of temperature in the body results in dis- 
turbance of the work of organs, and consequently in 
injury to health. Now, the chief purpose of clothing is 
to maintain the proper balance between the inner and the 
outer temperature of the body. Clothing does not create 
heat : it simply preserves it, regulates its radiation from 
the surface, and guards the body against sudden changes 
of its temperature. 

2. Clothing, by preserving the warmth of the body, is 
an economizer of food and of muscular and nervous force. 
It enables food to apply itself to the building up and re- 
pairing of the tissues, instead of being used up as fuel 
merely to compensate for a constant waste of heat. We 
cannot afford to overtax the body in making an undue 
amount of heat, nor can we afford to lose warmth faster 
than the body can properly make it ; and clothing saves 
the system extra labor by retaining its heat. Liebig, the 
eminent chemist, remarks that, " our clothing in refer- 
ence to temperature is merely an equivalent for a certain 
amount of food." Animals, unsheltered and exposed to 
the cold, lose fat and muscle ; but when properly shel- 
tered, they increase in these upon a smaller allowance of 
food. It is well known that human beings require less 
food, and are capable of more work, when comfortably 
clothed and warm than when too thinly clad and chilly. 

3. In order, then, that clothing shall fulfil its main pur- 
pose, we must give the most careful consideration to " what 
we wear, and to how and when we wear it." 



300 ACADEMIC PHYSIOLOGY. 

4. Essentials in Clothing Material. — Heat is conducted 
through some materials much more freely than through 
others. By interposing a non-conducting material between 
the surface of the body and the external air, we prevent 
the loss of heat which would otherwise result. Again, as 
a non-conducting substance prevents the escape of heat 
from within, it is equally effective in retarding the en- 
trance of heat from without. This is proved by ice being 
preserved from melting when wrapped in flannel or other 
woollen fabric, which retards for a long time the approach 
of heat to it. 

5. Men exposed to the intense heat of furnaces and 
steam-boilers almost invariably protect themselves with 
non-conducting, woollen garments. " The thick cloak 
which guards the Spaniard against the cold of winter is 
also, in summer, used by him as a protection against the 
direct rays of the sun." Hence, clothing should be of a 
material and texture which will serve this double purpose. 

6. In every case, it is the property which clothing mate- 
rial possesses of detaining air in its meshes, and allowing 
it to be exchanged slowly, that constitutes its value. A 
fabric while not being so loose in texture as to allow cur- 
rents of air to pass directly through it, should be so 
porous as to permit a constant but gradual change of the 
air in contact with the skin, and thus transmit the insen- 
sible perspiration without obstruction. " In one sense, 
perhaps, clothing is objectionable. It cannot be denied 
that if the skin could bear changes of temperature with- 
out danger to the system at large, the contact of fresh 
air would make it more healthful and increase its power 
of resistance." 

7. Materials for clothing differ widely as conductors of 



THE SKIN, CLOTHING, AND BATHING. 3OI 

heat and in other properties which also render them more 
or less valuable as coverings for the body. 

8. Properties of Woollen Clothing. — Wool, when man- 
ufactured into a soft fabric of porus texture, is an excel- 
lent non-conductor of heat and retainer of moisture, 
whether from within or from without. It is a much bet- 
ter protection against cold than cotton or linen of equal 
thickness. 1 When, however, wool is spun into a hard, 
worsted thread, and woven into a firm, compact cloth, it 
becomes a better conductor of heat, and is then not so 
well adapted for protection against cold. Fine wool, 
woven into loose, soft fabrics, is superior to all other 
materials, fur excepted, as a protector of the body against 
sudden changes of temperature. Flannel underclothing, 
varying in thickness with the different seasons 2 of our vari- 
able climate, should be worn next the body, summer and 
winter. Sometimes flannel irritates very delicate skins ; 
but this difficulty may be overcome easily by wearing it 
outside of muslin or linen, or, better still, by lining the 
flannel with silk. However, flannel in most instances 
soon ceases to irritate the skin, and becomes simply a 
means of keeping the surface stimulated. Even while 
perspiring, one may go into the open air of winter with 
much security, if clad in flannel. 

The outer clothing may be quite safely left to be de- 
cided by the comfort and taste of each person. As 

1 A tin vessel of hot water and covered with woollen cloth takes longer to cool 
than a similar vessel does when enveloped in cotton or linen fabric of equal thickness. 
Ice cannot be preserved more effectually in summer than by wrapping it in flannel. 

2 Thus Providence clothes the animals of cold climates with a shaggy covering 
from which those of the tropics are free. The coats of many animals in temperate 
regions change with the seasons, being close and longer in winter, thinner and shorter 
in summer. While we differ from the lower animals in habits, conditions, and sur- 
roundings, we may yet draw useful inferences from their economy. 



302 ACADEMIC PHYSIOLOGY. 

warmth, however, depends more upon the material than 
upon the quantity of the clothing, woollen outer clothing 
is superior to the other kinds ; and less of it is needed 
when the body is properly supplied with underclothing. 

9. Silk, Cotton, and Linen as Clothing. — Silk is a better 
conductor of heat than wool, but a poorer conductor than 
cotton. Its fibres are round and pliable, and it makes an 
agreeable garment for the skin. It ranks next to wool in 
suitableness for underclothing. It does not readily absorb 
moisture, and it gives a sensation of freshness to the skin. 
Like other material, its fitness for underwear is lessened 
when its threads are hard-twisted and woven into a com- 
pact fabric, for it then conducts heat more rapidly. 

10. Cotton is a better conductor of heat than wool or 
silk, but a poorer conductor than linen. It absorbs moist- 
ure less freely than linen does. When spun with a slack 
twist and woven loosely, it becomes a good non-conductor. 
Thus cotton flannels with a downy nap approach wool 
quite closely in suitableness for underwear, but are rather 
too heavy and become saturated with moisture ; but 
closely-woven muslin shirtings are but little better than 
linen in this respect, and are not fit to be worn next the 
skin. In the scale of values, cotton as clothing is inter- 
mediate between that of wool and silk. 

11. Linen conducts heat and absorbs moisture very rap- 
idly, and is therefore the poorest material for underwear. 
Retaining moisture which it absorbs, and parting rapidly 
with its warmth, it feels cold to the touch. Those who 
wear it next the skin are chilled after sweating, even in a 
hot day. It should not be worn next to the skin, except 
when covered by flannel, as before mentioned. Linen fab- 
rics of light color are, however, good reflectors of the 



THE SKIN, CLOTHING, AND BATHING. 303 

direct heat of the sun, and serve a good purpose as outer 
garments in summer. 

It should be understood from what has been said, that 
while materials differ greatly in their conducting proper- 
ties, the chief difference in the fabrics used for clothing 
lies in their porous texture, or in the amount of air con- 
tained in their meshes. 

12. India Rubber, and " Water-proof" Clothing. — The non- 
porous nature of India-rubber and other " waterproof " 
garments makes them very useful as a protection against 
rain and cold winds ; but they should be worn only when 
necessary to accomplish this purpose, and never longer 
than is required to do so. These impervious fabrics ex- 
cite very free perspiration, and at the same time prevent 
its evaporation, causing chill and liability to take cold 
after the garment is laid off. So far from healthful are 
rubber over-garments that their use has been forbidden in 
the French army. Undoubtedly the " abuse of the use " 
of such garments led to this prohibition. Rubber over- 
shoes are, for similar reasons, injurious when worn for a 
length of time ; they prevent all evaporation, and thus 
make the feet and stockings damp. " Arctics " made of 
lighter "water-proof" material are much less injurious, 
but even they should be worn as short a time as may be. 

13. Influence of Color in Clothing. — The color of outer 
clothing is more than a mere matter of taste and orna- 
mentation. It is a well-known fact that snow when cov- 
ered with black cloth melts sooner under the rays of the 
sun than when covered with a white cloth and similarly 
exposed. It has been ascertained by experiments made 
with shirtings of the same material exposed to the sun, 
that white received ioo° Fah., pale straw color 102, dark 



304 ACADEMIC PHYSIOLOGY. 

yellow 140, light green 155, dark green 168, light blue 
198, and black 208, the warmth of the fabric increasing 
with the depth of color. Hence, the color of clothing is 
of importance in a physiological sense. In tropical re- 
gions and during our warm summers, clothing is required 
largely as a protection against heat of the sun ; and a 
principal consideration is color, the best being white, and 
thence downward in the scale of value to black, which is 
the poorest. When not exposed to the sun, the influence 
of color in clothing is not marked. 

14. Common Errors in Dress. — Winter underclothing should 
be put on early and taken off late. It is much better to 
make a change of outer garments if a day be warm, or 
to increase the amount if the weather become suddenly 
colder. The great physician, Boerhaave, said, " Flannel 
should not be put off till midsummer's day, and should be 
put on — the day after. Only fools and beggars suffer 
from cold ; the latter not being able to get sufficient 
clothes, the other not having the sense to wear them." It 
is an error to make a sudden decrease in the amount of 
underclothing. 

15. The habit of clothing the upper portions of the body 
warmly while the legs and feet arc neglected is injurious. 
The clothing, especially in winter, should protect all parts 
so as to equalize warmth. Clothing the lower portions of 
the body too scantily results in driving the blood away to 
the upper portions, which then have too much of it and 
become over-sensitive. 

16. Swaddling the tJiroat and lower portions of the face 
with thick coverings in cold weather is generally an error. 
A thick veil worn over the face for a length of time de- 
prives the lungs and blood of much of the oxygen which 



THE SKIN, CLOTHING, AND BATHING. 305 

is food and life to them. Once begun, these practices 
must be continued, because the parts mentioned become 
over-sensitive to cold. Still, there is an exception to this 
rule. After speaking or singing for a length of time, it 
is unsafe to expose the throat to cold air or to breathe it ; 
the throat and vocal organs, being very warm from exer- 
cise, would be easily chilled. Protection should be had in 
this case, " not by wrapping a heavy scarf, or by buttoning 
a fur collar about the throat and mouth," but by envelop- 
ing the throat and lower part of the face in a large hand- 
kerchief, preferably one of silk, loosely cast about them. 
The breath, being directed against the covering, warms 
the air to be inhaled ; the mouth should be kept closed 
and breathing be carried on through the nose. It is a 
serious error to allow wrappings to remain about the 
throat long after entering a warm room ; this causes chill- 
ing on going out of doors 

17. The wearing of overcoats, cloaks, or other heavy 
street-garments, while in warm rooms, as in churches, 
theatres, etc., is a foolish and dangerous error. This 
practice, very common in our country, causes the blood- 
vessels of the skin to dilate, the perspiration to flow 
freely and to saturate both the under and intermediate 
clothing ; and in this condition of dampness, the wearer 
goes out to encounter the cold air. Such carelessness 
arises often from indolence, and is almost, sometimes 
quite, suicidal. Another error akin to the foregoing is 
the habit of removing outer garments in cold weather 
immediately on entering a house, or of passing out into 
the cold air at once after putting them on. This practice 
is a frequent cause of colds. 

18. It is an error a?id dangerous to believe that scanty 



306 ACADEMIC PHYSIOLOGY. 

clothing zuill " harden " or inure the body to cold and sudden 
changes of temperature without producing injurious effects. 
Jn the Highlands of Scotland, where the kilt, or short 
petticoat, scarcely meets the stockings of the wearer, 
rheumatism of the knees is quite common. The natives 
of Tierra del Fuego wear little or no clothing even in the 
coldest weather, but are dwarfed, hideous beings ; and the 
cattle of cold regions are small and stunted. Cold arrests 
development — "cold is death, heat is life." 

19. On the other hand, we may make ourselves tender by 
wearing too warm clotJiing. Those who always clothe 
heavily retain, in part, a "summer constitution," and can- 
not bear what others do when cold weather comes, or 
when the temperature falls suddenly. No exact rule can 
be given for the amount of clothing, other than that it 
should be regulated to suit our habits, health, and expo- 
sure, and be just sufficient to keep the body comfortably 
warm. By carefully adapting it to the coldness or warmth 
of the weather, we avoid necessity for hardening, and are 
less liable to become tender. 

20. Tight-fitting clothing does not protect against cold as 
well as looser clothing docs. Moderately loose garments 
allow a small space between them and the body, and the 
layer of warm air in this space preserves the warmth of 
the body. Loose gloves, for instance, protect the hands 
against cold much better than tight ones do. Clothing, 
night-garments especially, should not fit so tightly about 
the neck as to obstruct the circulation by pressure upon 
blood-vessels. Tight-fitting, uncomfortable clothing is, 
more frequently than we are aware of the fact, a source of 
irritability and bad temper. 

21. TigJit-fitting, heavy hats interfere with the circulation 






THE SKIN, CLOTHING, AND BATHING. 307 

in the scalp, and, by pressure upon blood-vessels and 
nerves, cause headache. Hats should be tolerably light 
in texture, or have means of ventilation in order to prevent 
overheating the scalp and inducing baldness. 

22. Tight -fitting boots and shoes, especially when they have 
narrow soles atid high heels, by pressure upon the skin and 
joints, cause corns and bunions. When too loose and 
ill-fitting, they chafe projecting portions of the feet, 
and sometimes cause troublesome sores. 

23. An excess of bed-clothing is as harmful as too little of 
it. It is natural to wish to become speedily warm after 
going to bed on a cold night ; and hence the temptation 
to use too many blankets, etc. At first the warmth is 
agreeable and not injurious ; but later, after one has been 
lulled to sleep, the excessive amount of clothing induces 
more or less profuse perspiration, while preventing its 
evaporation. The sleeper awakens unrefreshed and weak- 
ened, and is consequently very liable to take cold. 

24. Cleanliness and Care of Clothing. — All clothing should 
be kept clean. Underclothing, especially, absorbs perspi- 
ration and becomes charged with waste particles and the 
debris of the epidermis. Some of the poisonous products 
of this decaying matter may be absorbed through the skin 
and re-enter the blood, or at least by filling the meshes of 
the clothing prevent evaporation from the skin. A neglect 
to change clothing frequently is not only a filthy habit, 
but is a source of disease. Woollen clothing, in particular, 
when not purified by thorough ventilation and disinfection, 
has been known to convey the contagion of scarlet fever 
even three years after it was impregnated with the spores 
of the disease. 1 

I See directions for disinfection ~ of clothing, etc., in Appendix. Clothing in its 
relation to the framework, circulation of the blood, muscles, etc., is mentioned under 
the appropriate topics of our subject. 



308 ACADEMIC PHYSIOLOGY. 

25. TJiere should be an entire change of clothing on going 
to bed. The underclothing worn during the day should 
be aired and dried, and should be well shaken before being 
put on again. 

26. Night-clothing and the blankets and beds should be 
thoroughly aired every day, and refuse particles should be 
shaken out of them. Night-clothing not less than day- 
clothing becomes charged with impurities, and may become 
a source of disease. It is an error to " make up" beds 
soon after they have been occupied, thus shutting in the 
moisture and impurities that have been absorbed from the 
body. 

27. Wet clothing should be removed from the body at once. 
Indolent carelessness in not removing damp garments, 
shoes, and stockings immediately after entering the house 
frequently occasions the infliction of a severe penalty. A 
delay of five minutes may be sufficient to permit the con- 
gestion of an internal organ, for instance the lungs or the 
bowels, and lead to serious or fatal illness. Dry, well- 
warmed clothing should replace the wet, and the feet 
should be thoroughly rubbed and dried. In inclement 
weather young people are apt to enter the schoolroom or 
their homes in damp garments and with wet feet, and to 
remain in this condition for a length of time. This should 
never escape the notice of teachers and parents. At 
school the pupil should be required to dry his garments 
and feet, or should be sent home to do so. Wet garments 
abstract heat very rapidly from the body. 

28. When wet clothing cannot be changed at once, the per- 
son shoidd not sit still and shiver, but should exercise mod- 
erately, and in this way keep up the warmth of the body. 
It is well, too, to recollect the sailor's trick when wet 



SUGGESTED POINTS FOR QUESTIONS. 3O9 

clothing cannot be changed for dry — take off the wet 
garment, wring the water out of it, and put it on again ; 
it will be found to be much warmer. 

29. Poisonous Clothing. — The poisonous effects of cheap 
dyes, containing arsenic, copper, etc., in cheap, bright- 
colored clothing, should be known. Cases continually 
come to the notice of physicians in which colored gloves, 
stockings, tights, undershirts, hat -linings, etc., have been 
found to be poisonous, to cause eruptions, and to lead to 
eczema or other disease of the skin. Recently a Foulard 
cambric garment had been worn by a lady only a short 
time when she became seriously ill. There were found to 
be 5% grains of arsenic in one square yard of the cloth. 



Suggested Points for Questions. 

Chapter XXVII. — 1-4. Importance of the skin — protection, excretion, 
regulating of bodily temperature. Depression and imperfect work of skin. 
Melancholia — skin dense and inactive, cold and dampness as related to the 
skin, importance of securing free action of skin — clothing, bathing, friction, 
exercise. Parts of the skin harmoniously united, wear and renewal, elastic 
and resistant properties; functions mentioned in general; result of obstruc- 
tion. 5,6. Layers of the skin — number, names, difference, adherence, 
relation to underlying tissue; looseness in certain 'regions, suppleness desirable 
— instances. Modified skin — mucous membrane, nature of and location in 
general. 7-9. The derma — general character, fibrous structure, leather 
from derma. Connective tissue — fat deposit, etc.; papillae — appearance, 
disposition, arrangement, where numerous; epidermis dips between papillae. 
Organs of the derma — nerves, blood-vessels, glands, etc. 10-14. The epi- 
dermis — appearance, location, structure, office; unlike the derma — no fibres, 
but cells, varying thickness — why? Three layers of epidermis — horny, 
rete Malpighii, and pigmentary — location, appearance, structure, changes, 
etc., of each; varying color of the skin; epidermis removed — red appear- 
ance, and modifications, cause of; discolored marks on skin) — causes (note). 



310 ACADEMIC PHYSIOLOGY. 

Epidermis bloodless, nourishment of; blisters, scars from injuries — when. 
15. Muscles of the skin — amount, location, office in the lower animals and 
in the human. 

Chap. XXVIII. — 1,2. Vessels, nerves, and glands — object and respon- 
sibility of, in the skin; when their labor ceases. Vessels, etc., named. 3. 
Capillaries — abundant supply proven; capillaries in relation to papillae — 
course to veins. 4, 5. Nerves of skin — number, peculiarities of classes; 
tactile corpuscles — structure, location, number in different parts, function. 
Object of abundant nerve supply of skin — the skin and pain. 6-9. Seba- 
ceous glands — description of as to location, size, kind of secretion. Con- 
nection with the hair-pits and emergence to surface — number. Quantity of 
sebaceous matter and function. Glands inactive — result; obstructed — 
"skin-worms," pimples. Surplus sebaceous matter — removal; effects of 
neglect to remove — clogging, disease. 10-12. Sweat glands — location, 
structure, duct and opening; course through derma and epidermis — difference. 
Arrangement of openings on skin. Tube — diameter, length, total number, 
united length. Varying number in different parts; process of secretion of 
perspiration from blood — capillary surroundings of glands; constituents 
of perspiration. 13, 14. Forms and quantity of perspiration — constant 
secretion; sensible and insensible perspiration described. Quantity of per- 
spiration — comparative and daily ; amount varying — causes ; excessive perspi- 
ration and thirst — cause. 15. Absorption by the skin — function and where 
most active; medicines administered, thirst relieved, nourishment supplied — 
absorbed. 16. Breathing through the skin — experiment demonstrating the 
fact; condition of air enclosed around a body — gases interchanged. 17, 18. 
Functions of skin, lungs, and kidneys compared — similarity and in what 
respects; functions of skin and kidneys most alike; action of each in hot and 
in cold weather. Result of interruption of action of one set of organs — 
endeavor to compensate and how far possible; a varnish-covered skin — 
result; burned or scalded skin — result; importance of care of skin. 

Chap. XXIX. — 1, 2. Perspiration and heat — regulative agency of 
perspiration; uniform temperature maintained; average normal temperature 
of surface (note). Action of vaso-motor nerves when blood becomes heated 
— expansion of capillaries and increased secretion of perspiration; process of 
abstracting heat. 3-5. Perspiration and cold — contraction of blood-vessels 
and result; diminished perspiration — cause; radiation lessened. Sudden 
lowering of bodily temperature — effect of blood being driven to internal 
organs and weak spots. Fatal lowering. 6. Perspiration and dry air — 
rapid evaporation — cause; possibility of remaining in an oven when perspir- 
ing freely — instances and philosophy of; effect on temperature of blood. 7. 



SUGGESTED POINTS FOR QUESTIONS. 3 I I 

Perspiration and moist air — physical discomfort and cause; slow evaporation 
of perspiration; 8o° in damp air versus 90 in dry; workmen at furnaces and 
high, moist temperatures; "heat-stroke " and high temperature of moist air 

— bodily temperature then fatal. 8-10. The hair — appendage of epidermis; 
structure of hair — root, shaft, follicle, hair papillae, blood-vessels, nutrition; 
effect of destroying papillae. Canal of hair, cells and coloring matter. 
Diameter of hair, abundance, estimated number on head, enduring nature 
fnote). Functions of hair. 1 1— 13. The nails — composition, location on 
matrix, mode of growth — cell deposit, thinner at root — cause. Result of 
injury to matrix; injury at root; skin diseases affect nails; sickness affecting 
nail growth; nail disease, and effect of age. Functions of the nails; "club- 
ended" fingers — cause. 

Chap. XXX. — 1 . Hygiene of the skin — chief considerations — cleansing 
and regulating temperature of. 2-5. Cleansing necessary — matter deposited 
on the skin; sedentary life in warm rooms — deposits on skin. Poisonous 
matter absorbed by the skin — painters, etc. Impurity of blood from in- 
activity of skin — depression, headache. Health and a clean skin. 6-13. 
A warm bath for cleanliness — temperature and avoidance of shock and 
excessive stimulation; difference between warm and hot. Remaining too 
long in bath — proper time. Skin dried by friction — why and how. Fre- 
quency of warm bath — varying with condition; winter and summer frequency 

— gradual increase. Best time for warm bath — reason. Bathing immedi- 
ately after a meal — why improper. Use of soap in bathing — why; kinds 
and effects. 14. Hot baths — special benefits to be derived from; duration 
and method of taking — skin drying; promptly to bed; hot bath, etc., in 
breaking up a cold; frequent hot bathing improper — why. 15. Cold baths 

— first effects, shock, contraction of blood-vessels of skin, stimulated action 
of heart and lungs, reaction and warmth; bath end while glow continues — 
reason; friction beneficial. Tardy reaction injurious — congestion of internal 
organs — conclusion drawn. 17-19. Sea bathing— stimulating effect; bene- 
fit in weakness from rapid growth; caution required by the extremely nervous 
and in heart disease; medical advice as to bath by invalids. Manner of 
taking sea bath; comfortably warm on entering, activity while in — reason; 
shock and reaction followed by chilliness — danger signal; when bath should 
end; a cold, "still-bath," warm, salt-bath — for the weak. Frequency, 
time when, drying and friction. Care in diet at seashore. 20-23. Friction 
baths — body reacts slowly from cold in morning — reason; morning not best 
time for full bath. Wet friction bath in morning beneficial; method and 
appliances. Dry friction bath — method of taking; preparation of mittens 
for. Benefits of friction bath. -24-26. Washing of face and hands, cos- 



312 ACADEMIC PHYSIOLOGY. 

metics — effects of strong soap; use of soap — frequency; drying important 

— reason. Poisonous cosmetics — nature and effects; use of harmless face- 
powder; benefits of moderate friction; the most effective beautifiers. 27, 28. 
Care of scalp — importance of cleanliness; sources of refuse matter; unhealthy 
secretion — obstruction of pores. Brushing and brush; fine comb objection- 
able; washing of scalp; a valuable ointment and use of. Hair-dies — nature 
of, danger of use. 29, 30. Alcohol and the skin — paralysis of nerves; 
blunted sense of feeling and touch. Relaxed blood-vessels — flush; effects on 
temperature of skin — reaction and chill; reducer of warmth — danger in low 
temperatures; permanent congestion of capillaries — indication. 31. To- 
bacco — effects extending to the skin; pale, yellowish skin; skin of young 
smoker. 32. Diseases of the skin — whole system involved; diet, hygiene, 
and medicine necessary. 

Chap. XXXI. — 1-3. Object of clothing — ornament considered; preser- 
vation of health — balance between internal and surface temperature; result 
of disturbance; clothing a regulator — how. Clothing an economizer of food 

— philosophy; unsheltered animals versus sheltered; less food when com- 
fortably clothed. Importance of " what, when, how, ar 1 where." 4-7. 
Essentials in clothing material — conduction of heat; interposing a non- 
conductor — effects and demonstration; protection from heat by woollen 
garments — instance; the double purpose. Detention of air and slow ex- 
change — value; the desirable in texture and porosity — transmission of 
perspiration slowly. Wide difference as conductors, etc. 8. Properties of 
woollen clothing — when soft and porous — compared with linen and cotton; 
when closely woven and hard; value of flannel as underwear — varying thick- 
ness; irritation of skin temporary. Outer clothing a matter of comfort and 
taste; material versus quantity; woollen superior; quantity required. 9. 
Silk — as a conductor of heat; nature of fibres; agreeable to skin; rank in 
value; special properties; value dependent on texture — hard or soft. 10. 
Cotton — value as a conductor and absorber; when loosely twisted and 
woven; value of cotton flannel; when unfit for underwear; cotton in the scale 
of values, n. Linen — as a conductor and absorber; as underwear — unfit 
and why; value in light colors as outer clothing. Porous texture the chief 
difference in clothing values. 12. India-rubber clothing — protective nature ; 
limit in wearing — reason; unhealthfulness; rubber shoes — when injurious 
and why. 13. Influence of color in clothing — physiological importance and 
why; importance in summer, and scale of color values. 14. Winter under- 
clothing — when put on and when laid off — reason. 15. Scanty clothing of 
legs and feet — injurious and why. 16. Muffling throat and face — when 
improper and when prudent and why. 17. Wearing of over-garments in 



SUGGESTED POINTS FOR QUESTIONS. 3 1 3 

warm rooms — an error and why; too prompt removal. 18. Attempts to 
" harden " by scant clothing — injurious and why; instances illustrating. 19. 
Too warm clothing — effects of and cause. 20. Tight clothing as protection 
from cold — inefficient and why; as obstruction to circulation; irritability re- 
sultant. 21. Heavy, tight-fitting hats — objectionable and why; means of 
ventilation. 22. Tight-fitting boots or shoes — effects of; effects when too 
loose. 23. Excess of bed clothing — injurious and why. 24. Cleanliness 
of clothing as related to health — charged with waste products, absorption by 
skin; neglect to change clothing; contagion from clothing. 25. Entire change 
of clothing on going to bed — airing, drying, shaking. 26. Night-clothing 
and bed-clothing — airing and shaking and why; "making beds" too 
promptly — an error and why. 27. Removal of wet clothing — effects of 
neglect; sitting with wet feet; abstraction of warmth. 28. What to do when 
wet clothing cannot be changed at once. 29. Poisonous clothing — articles, 
poisonous dyes, and effects of. 



THE SPECIAL SENSES. 



CHAPTER XXXII. 

SIGHT. 

1. Sensation in General. — Our knowledge of the exist- 
ence and conditions of the various parts of the body, 
and of objects in the external world, is based upon sensa- 
tions through the nervous system as a medium. 

2. Many sensations are common to all portions of the 
body, and are not distinctly confined to a single organ or 
region at all times. Among these common or general sen- 
sations may be mentioned pain, fatigue, restlessness, hun- 
ger, faintness, etc. However real these sensations may 
be, they tell us nothing of objects external to the body. 

3. One of the common sensations is that peculiar one 
termed the muscular sense. The object of this sensation 
is to give a knowledge of the exact condition of the volun- 
tary muscles. By it the mind knows precisely the degree 
of contraction of any of these muscles, and the degree of 
resistance which arises when any obstacle is opposed to 
the movement of the body or any part of it. Thus when 
an arm is lying by the side, the mind is conscious of its 
position ; and when the arm is raised a shorter or a greater 
distance, a feeling of resistance to effort occurs. It is this 

3*4 



SIGHT. 315 

consciousness of the position of muscles and parts to 
which they belong, and of their exertion, which is named 
" the muscular sense." Except during the unconscious- 
ness of sleep, we are at all times cognizant of the position 
of the body and its limbs by means of the sense of con- 
traction or relaxation of the muscles. 

4. Special Sensations. — A number of sensations arise 
from impressions made upon definite parts of the body. 
Each of these sensations is produced by a stimulus ap- 
plied to that part of the body, and cannot be produced 
when applied to other parts ; in other words, the impres- 
sions are received by specially constructed organs of sense, 
so that they are distinctly local in character. Thus the 
sensations of taste and smell are confined to certain por- 
tions of the mucous membrane of the mouth and nose ; 
those of sight and hearing to the eye and ear ; and those 
of touch are restricted to the skin and to certain mem- 
branes lining the internal cavities. Any portion of the 
body to which a sensation is thus specially restricted is 
called a sense organ, and the sensations are called special 
senses. All the special sensations are referred to external 
objects or causes. 

The special senses are sight, hearing, touch, taste, and 
smell. 

5. The Sense of Sight. — First in importance among the 
special senses is that of sight. Through it are received 
the most varied and valuable impressions, and by it we 
become cognizant of objects around us, and are enabled to 
appreciate the beauties of form and color in nature. De- 
prived of it we should lose so much that is grand and 
beautiful i'n life, that to behold a blind person fills us with 
pity, while the thought of such an affliction falling upon 



3i6 



ACADEMIC PHYSIOLOGY. 



ourselves appalls the bravest mind. Sight and touch are 
very intimately related in some of their functions. 

6. Anatomy of the Eye. — Securely lodged in the cavity 
or socket prepared for it in the front part of the cranium, 
is that organ, marvellous in structure, which enables us to 
see. The eyeball is nearly spherical in form, and is pro- 
tected by the bony socket in which it is set, and by the cur- 
tains of cartilage and skin, the eyelids. To still further 
ward off insects, and veil it from dust or particles that 
might invade it, the eyelashes close and interlock when the 




Fig. 53. 



EXPLANATION. 

a, the lachrymal, or tear-gland, lying 
beneath the upper eyelid. 

b, b, the situation of the openings 
through which the tears flow into the 
tubes that convey them into the nasal 
sac and duct. 

c, c, the tubes continued from the open- 
ings. 

d, the nasal sac. 

e, the nasal duct, continued from the 
nasal sac. 

/, little canals that convey the tears to 
the eye from the gland. 



lids are brought together, while the eyebrows surmount all 
and aid in preventing perspiration from running into the 
eyes. To lubricate its surface and prevent friction against 
the lids, there is a watery secretion from the tear-gland. 
The eye is supplied with nerves and blood-vessels, and its 
freedom of motion in various directions is due to the action 
of muscles attached to its outer coat. 

7. The muscles of the eye are represented in Fig. 54. 
The natural appearance of the eye and accurate sight de- 
pend largely upon the harmonious action of the muscles 
which move the eyeball. When one muscle contracts 



SIGHT. 



317 



unduly, the eye is drawn out of the line of direct vision ; 
so also when a muscle is weakened and relaxed, the same 




Fig. 54. 



EXPLANATION. 



To the outer surface of the sclerotic coat are attached six muscles. Four of these are 
called straight muscles, two of which roll the eye upward and downward : the other two 
give it a sidewise motion to the right and left. The remaining two are called oblique muscles, 
and serve to roll the eye inward and downward. 



1, the muscle which raises the upper 
lid. 

2, the superior oblique muscle. 

3, the pulley through which its tendon 
plays. 

4, s, 6, straight muscles. 



to, inferior oblique muscle. 

u, the optic nerve (nerve of sight). 

[2, cut surface of cheek-bone. 

[3, opening of the nose or nasal ori- 



fice. 



condition is produced, in either instance causing strabis- 
mus, or cross-eye. 

8. The eyeball is about an inch in diameter, and, though 
apparently spherical, is really a little elongated from be- 
fore backward. It is composed of three tunics, or coats, 



3i8 



ACADEMIC PHYSIOLOGY. 



enclosing three refracting mediums, all being so arranged 
as to constitute a complex optical instrument. 

9. Coats, Humors, Lens, etc., of the Eye. — The outer layer 
of the eyeball, the sclerotic coat (Gr. sklcros, hard) which 
forms the posterior five-sixths of the ball, is a white, 
hard, fibrous structure continued in front by the cornea, 




Fig. 55. —Diagram of Vertical Section of the Eye. 



EXPLANATION. 



A , The Sclerotic Coat. 

B, The Choroid Coat. 

C, The Retina. 

D, The Optic Nerve. 

E, The Cornea. 



F, The Aqueous Humor. 

G, The Iris. 

H, The Ciliary Processes. 
I, The Crystalline Lens. 
K, The Vitreous Humor. 



(Lat. coma, horn) or transparent sixth, through which 
light passes to the interior of the globe. The part called 
the sclerotic coat maintains the shape of the eyeball, and, 
by its elasticity, controls the proper curvature of the 
cornea. It also affords attachment to the muscles that 
move the eye, and protects the more delicate parts within. 
The cornea forms the prominent curved surface of the 



SIGHT. 319 

front of the eyeball, and is the window of the eye, being 
as essential to sight as a window of a house is for the 
admission of light. It is not supplied with blood-vessels, 
but receives its nutrition by diffusion from other parts. 

10. The second layer is called the choroid coat (Gr. 
chorion, leather), and includes the iris (Lat. a rainbow), 
the curtain-like portion immediately back of the cornea. 
The choroid coat is a thin membrane containing a large 
number of minute blood-vessels, and is rendered opaque 
by a layer of dark-brown matter, called pigment-cells. 
One use of this coat is to darken the interior of the eye 
by absorbing all extra light, and thus prevent dazzling 
reflection that would confuse the sight. 

11. The iris is the thin, contractile, circular portion of 
the choroid coat situated between the cornea and the lens. 
It is perforated in the centre by a circular aperture, the 
pupil '(Lat. ptcpilla, puppet), for the admission of light. It is 
supplied with muscular fibres, some of which are arranged 
as a ring around the pupil, while the others radiate from 
it. The office of these little muscles is to regulate the 
quantity of light admitted into the eye ; thus the pupil 
contracts to exclude some of the light when too much is 
entering the eye, and dilates to admit more rays when the 
entering light is not sufficient to produce distinct vision. 
The curtain-like iris is lined behind by a dark substance, 
the thickness of which determines the color of the eyes 
of different individuals. 

12. The third coat of the eye, called the retina (Lat. 
rete> a net), is the delicate nervous membrane which lies 
within the choroid coat and forms the innermost layer 
of the eyeball. It consists of an expansion of the fibres of 
the nerve of sight, supported by an extremely delicate 



320 ACADEMIC PHYSIOLOGY. 

connective tissue. It is this nerve-membrane that re- 
ceives the images and transmits the impressions along 
the optic nerve to the brain, to produce the sensation of 
sight. 

13. The crystalline lens is a double, convex, transparent, 
solid body, close behind the iris. Its front surface, which 
is less convex than the back, is in contact with the iris, 
and a space is enclosed between these structures and the 
cornea in front. The lens is about one-third of an inch 
in diameter, is enclosed in a delicate membrane called 
its capsule, and has attached to it a strong, elastic frame, 
called the suspensory ligament, which is connected with the 
choroid coat. By the action of certain muscles and of 
this ligament the lens is made to change its shape (be- 
come more or less convex) and its position, so as to 
rapidly adapt the apparatus to long or to short ranges of 
vision. The office of the lens is to converge the rays 
of light to a focus on the retina, in order to produce a per- 
fect picture of the objects around us. 

14. The cavities or spaces within the globe of the eye 
are occupied by the aqueous and the vitreous humors. 
The aqueous humor (Lat. aqua, water) is a clear, watery 
fluid which fills the space between the cornea in front and 
the iris and lens behind; and the vitreous humor (Lat. 
vitreus, glassy) is the transparent, rounded, semi-solid sub- 
stance which fills the entire space behind the lens. The 
former of these humors (the aqueous) keeps the cornea 
in natural condition, and assists in maintaining its con- 
vexity; the latter (the vitreous humor) acts in slightly 
diverging the rays of light after they pass through the 
lens. 

15. Appendages of the Eye. — Among the appendages of 



SIGHT. 321 

the eye which demand special mention on account of the 
importance of their functions are the eyelids, the tear- 
gland, and the ducts related to it. Certain general func- 
tions of the eyelids, eyelashes, and eyebrows have already 
been stated. 

16. A thin mucous membrane, called the conjunctiva, 
lines the inner surface of the lids and the outer surface of 
the cornea and front part of the sclerotic coat. The part 
of this membrane that lines the lids contains many blood- 
vessels, and is very liable to inflammation. A number of 
small glands are situated in this membrane, and from these 
a number of small canals or ducts open on the edges of 
the lids and pour out a secretion to oil the lashes and 
prevent the lids from adhering together. 

17. The lachrymal gland (Lat. lachryma, a tear) is 
situated in a depression of the bone in the upper and 
outer portion of the orbit of the eye. It is about the 
size of an almond kernel, and secretes the tears, which 
are conveyed by several little ducts to the upper surface 
of the eyeball. Every motion of the eyelids assists in 
distributing the fluid over the surface of the eye till it 
reaches the inner corner of the eye, where it enters the 
mouths of two small lachrymal ducts, and is conveyed by 
them into the nasal duct and by it into the nose, having 
carried with it any particles of dust which may have 
adhered to the surface of the eye. If these ducts are ob- 
structed in any way, the tears must flow out and over the 
cheek ; and when an excessive amount of fluid is secreted, 
as in crying or through irritation of the eye, the surplus 
must flow over the lower lid because all cannot be con- 
veyed by the canal leading into the nose. 

18. The Phenomena of Sight. — Perfect sight is the result 



322 ACADEMIC PHYSIOLOGY. 

of a combination of various agents. In the first place 
there must be light. A body giving forth light sets 
waves in motion in that ether which surrounds us, in 
the same way that a stone thrown into the water propa- 
gates waves which expend themselves on the farther shore. 
Variations in the length of these waves produce varieties 
in the color of light, and also differences in its inten- 
sity. When a ray of light (or these vibratory waves) 
falls upon the eye, several phenomena occur, and the im- 
pression thus made is called a visual sensation, and is 
purely physical. Our recognition of the object is called 
a visual ' judgment ^ and is purely mental. 

19. The sensation caused by light continues longer than 
its presence. If two lightning flashes occur very nearly 
together they appear as one, the sensation caused by the 
first continues and is blended with that of the second. 
A lighted stick moved rapidly in a circle will, for like 
reason, present the appearance of a circle of fire. 

20. The degree of intensity of light depends upon the 
brightness of the object emitting it ; but there is a point 
reached at which an object appears no brighter, however 
much its inherent brightness may be increased. Thus 
the eye allows only a certain degree of stimulus, and be- 
yond the point where danger to its function might be 
induced, it refuses to recognize increased brilliancy. 

21. " Among the phenomena, all of which constitute 
sight, some belong to the domain of physics, and may be 
submitted to investigation ; many may even be demon- 
strated by experiment ; while others, on the contrary, are 
patent to the observation but little known as to their 
cause or mechanism." 

22. Visual Sensation, or How We See. — The phenomena 



SIGHT. 323 

that occur in the eye in receiving the impression pro- 
duced by light are as follows : Rays of light from an 
object pass through the transparent cornea and the pupil 
to the lens, which, like the lens of a camera, converges 
the rays and refracts them to a point on the retina, and 
this point is called the focus. In passing through the 
lens, the rays converge and then cross, and an inverted 
image of the object is produced upon the retina, just as 
the image is placed upon the screen of the photographer's 
camera. The impression made upon the nervous retina is 
communicated to the optic nerve, and by it to the brain, 
where it is recognized and becomes a visual sensation, or 
sight. 

23. The pupil has the power of contraction to enable it 
to adapt itself more completely to the amount of light, 
and to limit divergent rays. This is the first act of 
accommodation. In the second place, the lens can change 
its shape slightly so as to become more convex, and thus 
change its focal distance. This is the second act of 
accommodation. By these two means the eye accommo- 
dates itself to rays coming from a far or a near object. 
These movements of accommodation are rapid and not 
under the control of the will, but are responses to the 
stimulus of light. Certain poisons acting on the nervous 
system also cause contraction of the pupil. The oppo- 
site state, dilation, is produced by absence of light, by 
violent muscular efforts, and by the effects of certain 
other poisons on the general system. 

24. The retina is not equally sensitive in all its parts 
to light. A point in the retina very nearly opposite the 
centre of the pupil is much the most sensitive. A slight 
depression in the surface, marked by a pale yellowish color, 



324 ACADEMIC PHYSIOLOGY. 

indicates this point, and it is called the yellow spot. In 
looking at an object, that part of it which is in a straight 
line with the yellow spot and the centre of the pupil is 
most distinctly defined in the retinal image, — in other 
words, it is most clearly seen. This accounts for the fact 
that the eyeball naturally turns so as to bring the object, 
trie centre of the pupil, and the yellow spot into this line, 
the axis of vision. 

25. On the other hand, that point in the retina where 
the optic nerve enters the back of the eyeball is insensi- 
ble to light,' and is known as the blind spot. A very sim- 
ple experiment will furnish proof of this : On the page 
below we have placed a cross on the left side and a large 
dot on the right. Close the left eye, and look steadily 
with the right at the cross, holding the page at a distance 
of ten or twelve inches. 



Both dot and cross are thus seen quite distinctly. 
Now, move the book very slowly toward the eye, keeping 
it still fixed upon the cross. At a certain distance — 
generally about six inches — the dot at the right will sud- 
denly disappear, owing to its image falling on the blind 
spot ; but on bringing the page still nearer the eye, the 
image of the dot leaves the blind spot, and is again 
perceived. 

26. The sensibility of the retina is readily exhausted by 
excessive light. In looking at a very bright light for a 
time, that portion of the retina on which the light falls 
soon becomes insensible, so that in turning from the 
light and looking at a white surface a dark spot appears. 



SIGHT. 325 

The rays of light from this surface fall upon the exhausted 
point in the retina, and produce the appearance of a dark 
spot, precisely as in the absence of rays. 

27. Normal-Sight, Near-Sight, and Far-Sight. — Ordinarily, 
or in normal sight, the eye can adjust itself to see dis- 
tinctly objects that are brought as near as five or six 
inches; but when objects are brought still nearer, sight 
becomes blurred and indistinct. Again, it can also adjust 
itself for objects at a very great distance, any indistinct- 
ness of the images produced on the retina being due to 
their minuteness, but not to any want of proper focusing 
of the eye. The range of sight of the normal eye, when 
we read or write, is about fourteen inches. Some people, 
however, are born with, or afterward come to possess, 
eyes in which the limit of distinct sight is much closer, 
sometimes as near to the cornea as one or two inches, 
and such eyes are said to be near-sighted} 

28. In near-sightedness the cause is not always the 
same ; but in the majority of cases the condition results 
from a too great convexity of the cornea and lens, or from 
an elongation of the eyeball from front to back, thus 
making the distance between the lens and the retina too 
great. In either case the rays of light come to a focus 
before reaching the retina (somewhere in the vitreous 
humor), and consequently no image of a distant object is 
produced on the retina. To* remedy this difficulty, con- 
cave glasses, which properly diverge the rays and thus 
prevent the focus before reaching the retina, should be 
worn by near-sighted people. 

29. On the other hand, there are many people who 
cannot see near objects distinctly, while distant ones are 

1 Myopia, or short sight. 



326 ACADEMIC PHYSIOLOGY. 

clearly seen. Unassisted by glasses, they hold a printed 
page, or other ordinary object, at an unusually great dis- 
tance from the eye in the effort to see distinctly. Some 
people are born with this defect of sight, but most people 
encounter it as age advances ; and hence it is known as 
far-sight or old sight. 1 In far-sightedness the cornea, or 
the lens, becomes less convex, or the eyeball shorter from 
front to back, than when in a normal condition ; the lens 
being too near the retina, the rays do not focus on reach- 
ing the retina so as to produce a clearly defined image of 
near objects. In such cases, convex glasses should be 
worn to assist in converging the rays on the surface of 
the retina. In the same person, one eye may be near- 
sighted and the other far-sighted, necessitating the use of 
a concave glass for one eye, and a convex glass for the 
other. 

30. Recognition of Color and Color-Blindness. — What charm- 
ing variety is given to the objects in the world around 
us by the colors they exhibit ! A colorless world would 
be a dismal abode. Shades of darkness would afford a 
delightful variety in comparison. 

31. A ray of pure light as it comes from the sun is 
white. While we cannot discuss here the theory of light 
and color, it must suffice to say that the colors of the 
spectrum, or the rainbow colors, are blended in an infinite 
number of ways, giving rise -to all the shades and tints we 
observe in nature. 

32. The colors of objects are due to the wave-lengths 
they set up in the ether which carries the impulse to the 
eye. The falling of these waves, or vibrations, upon the 
expansion of the retina is sufficient to give rise to all 

1 Presbyopia, or long sight. 



SIGHT. 327 

those feelings which we term sensations of light and 
color. 

33. Color-blindness is a difficulty, more or less great, in 
distinguishing colors, some of which are entirely con- 
founded by many people who are color-blind without 
knowing it. The most common form is an inability to 
distinguish between rose and gray, or red and green. 
It may arise in a defect in the retina which renders that 
organ unable to respond to different vibrations of light, 
and consequently insensible to red, green, or other rays, 
or in some fault in the conduction of the impulse to the 
brain. It is not possible to state in what the disability 
absolutely consists ; but it is a lack of power in some part 
of the optic apparatus to discriminate or co-ordinate the 
sensations. A physical cause inherent in the individual 
is probably at the bottom of it. 

34. While color-blindness is merely unfortunate for 
most people in whom it exists, it may become exceedingly 
dangerous when either knowingly or unknowingly pos- 
sessed by railway employees or by those in charge of ves- 
sels upon the waters. Human life and valuable property 
often depend upon the ability to recognize the colors of 
lights without mistake. 

35. Visual Judgments. — The knowledge we obtain con- 
cerning the form, size, distance, and color of objects is 
called visual judgment. An infant sees a ball which to 
him seems near, yet is really so distant that his struggling 
efforts to clutch it are futile. It appears to him flat, or a 
mere disc, and he cannot discriminate between its color 
and one of another color. He may see the difference 
but cannot recognize it again, at once. In short, he 
has a visual perception, but has not yet attained visual 
judgment. 



328 ACADEMIC PHYSIOLOGY. 

36. Visual judgment is the result of the association of 
other senses with that of sight in regard to the size, form, 
distance, etc., of objects. We measure the distance of an 
object with the eye by movements of the eyeball and by 
adaptation of parts, so that the object is properly focused. 
We measure the object itself, the distance of its various 
parts from the eye, and in this way also obtain an idea of 
its form. We appreciate its color by the wave lengths it 
brings to the eye and impresses upon its sensitive retina. 
We know, for instance, the size of an object near the eye, 
and we thus gauge its size, when further removed, by 
this standard distance. When the object is removed to a 
greater distance it appears smaller ; but we know, through 
repeated experiences, that it is not smaller, and that all 
objects afar off look smaller than when near. Hence 
the element of distance comes in to modify our estimate 
of size, and we form a visual judgment from previous 
experience. 

37. We further obtain by the sense of touch a concep- 
tion of the shape of an object. A repetition of such 
experiences becomes an impression stored in the mind. 
So the appearance of a round or a square body becomes 
known to us by means of the rays of light which proceed 
from it, without having to confirm our visual judgment 
by aid of any other sense than that of sight. 

38. An object is usually viewed with both eyes, and 
this assists very much in forming our ideas of its shape 
and size. Thus when a body of moderate size, which has 
been ascertained by touch to be solid, is viewed with both 
eyes, the images of it formed on the retinas are neces- 
sarily different, one showing more of its right side, the 
other of its left. Notwithstanding, the images are cast 



SIGHT. 329 

upon corresponding parts of the two retinas, and are com- 
bined into a single Image which gives the impression of 
solidity. The well-known instrument called the stereoscope 
is constructed on this principle, being so contrived as to 
throw the images of two pictures of a solid body upon the 
retinas of the eyes in the same way that these would be 
received if they really proceeded from one solid body. 

39. The connection between the impressions forwarded 
by the retina through the optic nerve and that act of the 
brain itself which constitutes the true sense of sight, is 
mysterious. We only know that it is the brain that sees ; 
that though the eyes be open during sleep, no evidence is 
shown that sight is present, or that recognition is taken 
of objects placed before them. 

40. Optical Delusions. — Delusions of the judgment 
through the sense of sight, called optical delusions, are 
more numerous than those of any of the other senses. 
This arises from the fact that so great a number of what 
we think to be simple sensations of sight are really very 
complex combinations of sight, touch, and recollections of 
former sensations and judgments, all tending primarily to 
confusion of visual judgment, or optical delusion. It is 
not necessarily a derangement of the nervous system that 
causes delusive visions. People in the full possession of 
their faculties and of high intelligence may be subject to 
such appearances. 



330 ACADEMIC PHYSIOLOGY. 



CHAPTER XXXIII. 

HYGIENE OF THE EYE AND CARE OF EYESIGHT. 

1. Conditions Essential to Perfect Sight. — In many cases, 
even in the young, there is some abnormal condition 
affecting the sight. In studying the structure of the 
eye we found a number of parts the perfect condition 
and correct relative positions of which are necessary for 
perfect vision. Thus, the cornea must be properly curved 
and perfectly transparent ; the aqueous humor must be 
clear and sufficient in quantity to fill its proper space ; 
the iris must hang perfectly free, and the pupil be capable 
of contraction and dilation under the stimulus of light ; 
the lens must be perfectly transparent, and capable of 
adjustment to long or to short vision ; the vitreous humor 
must be transparent ; the retina must be free from con- 
gestion, and adhere to the choroid coat; the dark pig- 
ment of the choroid must be sufficient to absorb light and 
prevent its reflection ; and finally, the optic nerve must 
be healthy, in order to conduct impressions correctly from 
the retina to the brain. Any defect in these conditions 
constitutes disease, and necessarily renders sight imperfect. 

2. Rules to be observed in the Ordinary Care of the Eyes. 
— When we observe how little attention is given to the 
proper care of the eyes, and how greatly many people 
over-tax them under improper conditions of light and posi- 
tion, we should not be surprised that there is so much 



SIGHT. 331 

defective sight, and that diseases of eyes are so numerous. 
While defects of vision are frequently inherited, much 
imperfect sight is induced by lack of ordinary care or by 
abuse of these organs. Thus, the majority of persons 
appear to consider it necessary to face a strong light in 
order to see distinctly while reading, or when performing 
any kind of fine work. Many others strain and weaken 
their eyes by reading in railway cars where the jarring is 
so great as to render it impossible to hold the page 
steadily, or to keep it at a proper focal distance. Others, 
through carelessness or uncleanliness, convey poisonous 
or irritating substances into the eyes by unwashed fingers ; 
and very frequently a particle of dust lodged in the eye 
causes still others to indulge in vigorous and continued 
rubbing which irritates and inflames the membranes to 
such an extent that sight is temporarily lost. These, and 
other similarly careless abuses of the eye and sight, are so 
important as to require a few general guiding rules for 
the care of the eyes : — 

3. Regarding the position of the body in relation to the 
light, the left side or the back (preferably the former) 
should be turned toward the light, whenever it is possible, 
so that the eye may be protected from excessive light, 
while the book or work is fully and properly illuminated. 
This rule applies both to sunlight and to artificial light. 
In facing a strong light, the pupils contract to shut out a 
portion of it, and thus the rays from the object viewed 
are also shut out to some extent, causing the sight to be 
less distinct. When it is not possible to avoid facing the 
light, shades should be so employed as to screen the eyes, 
while admitting of the illumination of the object under 
view. School desks should invariably be so placed that 



332 ACADEMIC PHYSIOLOGY. 

the pupils may receive the light from windows on their 
left. In short, irritation and weakening of the eyes and 
impaired sight may be avoided by taking proper position 
in relation to the light. 

4. While a book or paper is being read, it should be 
held, or otherwise kept steadily and firmly, at the proper 
focal distance from the eyes. If this is not done the eyes 
are weakened, and soon permanently injured, by the irri- 
tation caused by the rapid and continuous changes of their 
adjustment in the effort to retain the focus of the print. 
Inclining the head too far over the book or work tends to 
cause congestion of the blood-vessels of the eyes, and 
should be avoided. 

5. The eyes should not be frequently or continuously 
employed when light is deficient, or lacking in uniform 
brightness. Efforts of the eyes to see under such condi- 
tions are very taxing on their powers, and weakened sight 
is the consequence. 

6. When the eyes are employed upon fine work, they 
should be rested occasionally in looking at more distant 
objects, or by closing the lids and thus obtaining momen- 
tary repose. This should be done before the eyes begin 
to feel wearied by long-continued application. 

7. The hands should be carefully washed after handling 
any poisonous or irritating substance, and especially after 
dressing a sore or other diseased part from which there is 
a discharge of matter. If this is not done, particles of 
poisonous substances that adhere to the fingers may be 
conveyed to the eyes and cause serious inflammation. A 
towel that has been used by a person who has sore eyes 
should not be used by another until after it has been 
thoroughly washed; and the wash-bowl or basin should 
be similarly avoided. 



sight. 333 

8. When cinders, dust, or other particles get into an 
eye, rubbing should be entirely avoided, as it causes in- 
creased irritation and does not help to remove the intruder. 
If the lids can be closed for a few moments, an increased 
flow of tears will probably wash the irritating particle 
toward the inner angle of the eye, from which it may be 
removed by wiping with a soft handkerchief. If this pro- 
cess fails, the lower lid may be pushed upward, while the 
upper lid is drawn outward and downward so as to overlap 
the lower lid, thus causing the lower lashes to sweep the 
eyeball and the under surface of the upper lid, and to re- 
move any particles that may be adhering to the surfaces. 
If the object is under the upper lid, it may also be readily 
removed by turning the lid upward over a pencil, or 
similar instrument, and wiping the surface with a soft 
handkerchief. 

9. If a piece of steel, glass, or any other hard substance 
becomes imbedded in the eye-ball so that it cannot be 
safely removed by simple means at hand, the eye should 
be closed and covered with a dampened cloth, and pre- 
vented from moving by a slightly compressing bandage 
till a competent surgeon can be consulted. 

10. If lime or any other caustic substance gets into the 
eyes, the lids should be opened immediately, and sweet 
olive oil freely applied to the irritated parts. If the oil is 
not obtainable at once, bathe the eye similarly with a weak 
solution of vinegar in water (a teaspoonful of vinegar to 
half a glass of water), and consult a physician as soon as 
possible. 

11. Whenever the eye has sustained an injury of any 
kind that appears, or is, at all serious, it should be loosely 
bandaged in order to exclude light and prevent motion ; 



334 ACADEMIC PHYSIOLOGY. 

after which the services of a surgeon should be sought 
immediately. It is best to recollect in all such cases, that 
delay is probably fraught with danger, especially in rela- 
tion to so delicate an organ as the eye. 

12. In reading while lying down, the book or paper can- 
not easily be held in the position and at the distance 
required for the accommodation of the muscles and other 
apparatus of the eye, and they are over-strained. This 
habit should be abandoned by all who would retain unim- 
paired sight. 

13. The eye and its appendages require cleanliness, 
and should be carefully bathed to remove dust and impu- 
rities. Moderately cool water is the best eye-wash for 
healthy eyes. 

14. Whenever the sight shows a tendency to become 
imperfect, consult an oculist without delay in order that 
timely means may be employed to restore its powers, or 
to prevent further impairment. 

15. An eminent oculist advises persons desiring to re- 
tain good eyesight to avoid the use of stimulants and nar- 
cotics (alcohol, tobacco, etc.) ; to avoid sudden changes 
of extremes in light ; to avoid reading while lying down ; 
to rest the eye by looking at objects at a distance ; to be 
careful in matters of hygiene in relation to general health, 
as these are intimately related to good sight; to bathe the 
eyes twice a day in cool water until about forty years old, 
after which age bathe them with warm water ; do not rely 
entirely on your own judgment in the selection or use of 
glasses, and do not be afraid of an operation for the re- 
moval of cataract. 

16. Defects of Sight requiring Spectacles. — The tendency 
of a neglected defect in vision is toward increased defect. 



sight. 335 

Certain defects, as we have seen, may be corrected by the 
use of suitable spectacles, and their importance as a cor- 
recting agent cannot be over-estimated. The eyesight of 
thousands of persons, young and old, becomes further im- 
paired by delay in procuring and using properly selected 
glasses. In many cases, defect in sight is first experienced 
in attempting to read small print, or in doing fine work by 
a dim or artificial light ; and in such instances, if the use 
of glasses is postponed for any length of time, the eyes 
change rapidly and will soon require more powerful lenses. 

17. In the selection and use of glasses when vision be- 
gins to be impaired, the following rules prescribed by 
ocular science should be observed : — 

First, as soon as it becomes evident that it is necessary 
to hold ordinary print either nearer to or farther from the 
eyes than formerly, or as usual in good sight, procure 
properly adjusted spectacles, intrusting their selection only 
to a competent oculist or optician. 

Second, spectacles should not be used during clear day- 
light until it is discovered that the object needs to be 
brought nearer the eye than formerly ; or in other words, 
till the "near point" begins to recede. 

Third, single eye-glasses should never be used (espe- 
cially when the eyes are equal in power), as they give rise 
to a difference in the focal distances of the eyes. 

Fourth, in far-sightedness the glasses used in viewing 
near objects should not be employed for viewing distant 
ones. 

Fifth, ordinarily the first spectacles used should not 
magnify, but merely rest the eyes while viewing small ob- 
jects. For this purpose, lenses of very low power should 
be selected. 



336 ACADEMIC PHYSIOLOGY. 

18. Eyesight usually begins to fail naturally between 
the ages of thirty-five and fifty, varying according to the 
habits and occupations of different individuals. 



CHAPTER XXXIV. 

HEARING. THE EXTERNAL AND THE MIDDLE EAR. 

1. Location of the Ear, etc. — The organ of hearing, the 
ear, is probably the most complicated organ of special 
sense. It is not placed on the face, like those of sight, 
smell, and taste. Its most delicate and important parts lie 
deeply hidden in the hardest bone of the body, at the 
base of the skull ; but still we may say that, in a sense, 
it belongs to the face because of the part it plays as 
one of the elements of physiognomy, contributing not 
a little to the expression of the face and head in general. 
The pavilion of the ear stands out from the head and is 
projected forward, its outline being in beautiful harmony 
with the contour of the skull and oval of the face ; and 
the artist studies the auricle in its relation to these. Any 
departure from its normal outlines is at once recognized 
as an incongruity ; and thus in the famous statue of the 
Faun, by Praxiteles, the pointed tops of the ears give to 
the whole a weird and inhuman expression. 

2. The location of the innermost regions of the ear, 
deep in the solid bone of the skull, has made the extremely 
complex nature of these parts all the more difficult to 
study. Anatomically, the ear is divided into three regions, 
called respectively the external, the middle, and the internal 
ear. 



HEARING. 



337 



3. Divisions of the External Ear. — The external ear com- 
prises the auricle (the part commonly called "the ear") and 
the auditory canal. The tympanic membrane, or drum- 
head, stands as a partition between the external and the 
middle ear. at the inner end of the auditory canal. 

4. The Auricle. — The auricle is a curiously formed shell 
of cartilage covered with skin which closely fits all the 




Fig. 56. 



EXPLANATION. 



a, the external ear. 

b, the canals of the labyrinth. 

c, the auditory canal. 

e, the anvil-bone. 

f, the cochlea. 



g, the tympanic membrane, 
k, the middle ear (tympanum), in which 
the little bones are placed. 
i. the Eustachian tube. 



ridges and grooves of the underlying gristle. Concave 
on its outward and forward surface, and convex on the 
opposite side, its shallow, trumpet-mouth form serves as 
a collector and strengthener of the weaker sounds which 
fall upon it. — sounds that, in the absence of the auricle, 
would be lost to hearing. 



33$ ACADEMIC PHYSIOLOGY. 

The surface of the auricle is covered with downy hair, 
and at the entrance of the canal there are stiff hairs which 
might be called the "lashes "of the ear. These latter 
aid in protecting the ear against entering dust, insects, 
etc. 

5. The Auditory Canal. — This canal may be said to be 
the tube of the acoustic trumpet, of which the auricle is 
the flaring mouth. It is a tube about an inch and a quar- 
ter long, and one-quarter of an inch in diameter, closed at 
its inner extremity by the drum-head. (See Fig. 56.) 

6. The lining-skin of this canal contains, in addition to 
the glands common to the skin, the ear-wax glands, of 
which there are more than one thousand. 

7. The wax-glands resemble the sweat-glands in struc- 
ture, and they secrete and pour out the ear-wax, which is 
of the greatest importance to the health and comfort of 
the passage. Smeared with this wax, the skin of the 
outer end of the canal is free from irritation and itching ; 
and the glutinous and peculiarly bitter nature of the wax 
is a protection against the entrance of insects. 

8. In addition to its function of conducting sounds, the 
auditory canal has the ability to cast out surplus wax that 
accumulates in it. The mouths of the wax-glands lie 
near the entrance of the canal. From this point out- 
ward the canal inclines, or is " down-hill," while in the 
opposite direction it slopes toward the drum. This being 
so, any loose particle of wax naturally tends to slide or 
roll out of the ear. Such particles will not pass inward, 
"up-hill," unless pushed in, as is often the case in at- 
tempts to remove them by means of ear-picks, pin-heads, 
etc. Furthermore, the skin of the drum-head and of the 
canal grows outward, and has a tendency to carry out dirt 



HEARING. 339 

and wax, thus doing its own sanitary work when not inter- 
fered with by unnecessary swabbings and scrapings. 

9. The Tympanic Membrane, or Drum-Head. — This mem- 
brane is the dividing partition between the auditory 
canal and the drum-cavity of the middle ear. It is 
nearly circular, and about one-fourth of an inch in di- 
ameter. It consists of three layers, the outer one a 
continuation of the skin of the canal ; the middle one of 
fibrous tissue (the thickest layer) ; and the inner layer 
of mucous membrane. Its edges are attached to a bony 
rim in the side of the skull. 

10. Stretched somewhat like the head of an ordinary 
drum, it performs similar service. The sound-waves beat 
upon it and cause it to vibrate, back and forth, thus com- 
municating motion to the chain of little bones, the first 
link of which is attached to its inner surface. The vibra- 
tion of this membrane is the first step in the process of 
bringing the impulse given by the air-waves into contact 
with the nerve of hearing. 

11. Divisions of the Middle Ear. — The middle ear is lo- 
cated, as its name would imply, between the external ear 
and the internal. ear. It is a small, irregular air-chamber, 
hollowed out in the hard portion of the temporal bone, 
and its principal occupants are the little bones of hear- 
ing, the smallest bones of the body. The middle ear 
comprises the tympanum and its important adjuncts, the 
Eustachian tube and mastoid cells. 

12. The Tympanum, or Drum. — This cavity is nearly half 
an inch in height and in length, and from a twelfth to a 
sixth of an inch in depth. It is lined with mucous mem- 
brane, and is the most delicate and complicated division 
of the middle ear. It is the drum proper, and is the only 



340 ACADEMIC PHYSIOLOGY. 

part of the ear to which the term '• drum " should be ap- 
plied. Confusion results from speaking of the tympanic 
membrane as being "the drum." This cavity and its ap- 
purtenances are the portions of the ear most liable to 
diseases. 

13. The ossicles, or auditory bones, are four in number, 
and are joined together so as to form the so-called " chain 
of bones " stretching from the drum-head through the 
drum-cavity to another membrane which covers a small 
hole in the opposite side of the cavity. These bones, 
named from their resemblance to the implements, are the 
hammer, or malleus ; the anvil, or incus ; the round bone, 

/-> r or orbicularis (the smallest bone) ; and the 

^==\\ <r* stirrup, or stapes. (Fig. 57 represents these 

< a bones of their natural size, except the round 

^> bone, which is magnified. Passing into the 

F,g ' 57 ' drum, the first bonelet of the chain we meet 

is the hammer, the largest of the four, being about a 

quarter of an inch long, and having its handle attached to 

the inner surface of the drum-head. Next in order is the 

anvil, which is a little smaller than the hammer. Third 

comes the round bone (found in the ear of- the young, but 

later it becomes part of the anvil) ; and fourth the stirrup, 

whose foot-plate is firmly joined to the membrane (similar 

to the drum-head) in the opening into the inner ear. 

14. Joined one to an extremity of another, they form a 
bridge between the drum-head and the entrance to the 
labyrinth, and are held in position by ligaments which 
fasten them to the roof and walls of the drum-cavity. 
When the drum-head vibrates under the force of a sound- 
wave, the linked bonelets swing inward and transmit the 
vibrations to the membrane in the oval window of the 



HEARING. 341 

labyrinth, or internal ear, and thence make an impression 
upon the nerve of hearing. 

15. The Eustachian Tube. 1 — This tube is the only natural 
air-duct between the throat and the drum-cavity. Open- 
ing in the back of the throat (pharynx), above the palate 
and a little below the floor of the nostrils, it passes up- 
ward, outward, and backward to the middle ear. Its 
length is somewhat more than an inch ; and its open- 
ings in the throat and in the drum are wider than the 
"isthmus," midway of its length, where it is one-sixteenth- 
of an inch wide. About two-thirds of the tube is cartilage, 
the third next to the ear being bone. 

16. Every act of swallowing has the effect of opening 
the mouth of this tube in the throat ; air then enters it 
and passes through into the drum-cavity, thus keeping the 
pressure of air equal upon t'he inner and outer sides of the 
drum-head. In the military drum this is provided for by 
means of a hole in the side, which allows air to pass freely 
in and out, in order that the vibration may be perfect. 

17. The air within the drum-cavity is soon absorbed 
and a partial vacuum is caused, when, for any reason, the 
Eustachian tube is closed. The pressure of air upon its 
outer side then forces the drum-head inward, the little 
bones are pressed upon each other, and so locked as to be 
unable to swing freely ; hence, a closure of this tube is a 
common source of deafness. In yawning, the tube is com- 
pressed and its walls adhere for the moment, causing the 
peculiar roaring in the head that all have experienced. A 
crackling sound is heard on the removal of the compres- 
sion, and all is right again. 

1 Eustachian, from Bartholomeo Eustachi, a celebrated Italian anatomist (died 
1574) who first gave a description of the tube. 



342 ACADEMIC PHYSIOLOGY. 

18. A blow upon the ear, or an explosion, forces the 
drum-head suddenly inward, driving the air in the drum- 
cavity into the Eustachian tube, and even into the throat, 
thus allowing the drum-head to "give " and saving it from 
rupture. Gunners, often without knowing why, open their 
mouths when firing, and thus allow unobstructed egress of 
air from the Eustachian tube. 

19. The Mastoid Cells. — These are a set of spongy bone- 
cells within the cavity of the mastoid-bone, which may be 
felt as a rounded prominence back of either ear, and they 
are lined, like the drum-cavity, with mucous membrane. 
These cells contain air, and unite with the Eustachian 
tube by a sort of funnel. The function of these cells is to 
increase the amount of vibratory surface, and thus to aid 
in hearing deep tones ; for, in order that the drum may 
properly receive deep sounds, it must have depth and 
capacity, and hence its connection with the mastoid cell- 
cavities. 

20. On its inner side a very thin wall of bone separates 
the mastoid cavity from one of the large blood-vessels of 
the brain ; and, as this cavity readily partakes in the dis- 
eases of the drum, this thin wall soonest gives way to dis- 
ease, and infectious matter thus passes from the cavity to 
the brain. 



HEARING. 343 



CHAPTER XXXV. 

THE INTERNAL EAR, AND HOW WE HEAR. 

1. Divisions of the Internal Ear, etc. — The labyrinth} or in- 
ternal ear, is, as its name indicates, an extremely compli- 
cated division of the organ of hearing ; and the functions 
of many of its parts are not clearly known. It consists of 
a central cavity which communicates with spiral tubes and 
winding channels, all of which are lined with mucous 
membrane and filled with water. The filaments 2 of the 
nerve of hearing are spread out in the lining of these pas- 
sages ; and it is the function of the internal ear to receive 
the impressions of sound and to transmit them, by means 
of the auditory nerve, to the brain. While the middle ear 
is an air-chamber, the internal ear is a water reservoir. 
Its divisions are a central chamber, or vestibule ; the spi- 
ral tubes, or cochlea ; and the semi-circular canals — all 
forming a continuous cavity. 

2. The Vestibule. — This is the central, egg-shaped por- 
tion of the labyrinth between the semi-circular canals 
and the cochlea. It communicates with the drum-cavity 
by means of two small openings, which, from their shapes, 
are called the oval window and the round window. In the 
living body these " windows " are closed by firm mem- 

1 Lab'-y-rinth (Gr. laburin'thos). A maze ; a building with many winding 
passages. 

2 Fil'-a-ments, tiny, thread-like ends. 



344 



ACADEMIC PHYSIOLOGY. 



branes, similar to that of the drum-head. The foot-plate 
of the stirrup-bone is joined firmly to the membrane of 
the oval window, and thus the connection between the 
drum-head and the labyrinth and nerve of hearing is made 
complete by the chain of little bones. 




Fig. 58. — Interior of the Left Labyrinth, highly magnified. 

EXPLANATION, 
a to a, the cochlea ; k, the hollow axis about which the two canals wind two and a half 
turns ; i to 4, the semi-circular canals ; m, the vestibnle, in which are n, the fenestra ro- 
tunda (round window), and o, the fenestra ovalis (oval window). 



3. The Cochlea, or Snail-shell. — This portion of the inter- 
nal ear is a bony tube twisted two and a half times about 
a bony pillar, being similar to a snail-shell. It is divided, 
in part, into two spiral passages by a bony shelf. If an 
insect could leave the vestibule opposite the oval window, 
it might pass into the upper of these spiral stairways, 
crawl to the summit, and descend by the lower stairway to 
the round window. 



HEARING. 345 

4. The nerve of the cochlea, after passing into the bony 
pillar, divides into many tiny branches of varying length 
which spread out upon the bony shelf, like the strings of 
a harp or piano, and form the so-called "organ of Corti." 
Physiologists have reason to think that this organ is spe- 
cially designed to receive impressions of musical sounds as 
distinguished from others which are received by the nerves 
of the vestibule. 

5. The Semi-circular Canals. — This is the name given to 
three curved tubes. They are each enlarged into a bulb- 
ous cavity at one extremity. 

6. It has been found, through experiment, that when 
these canals in the ears of birds, or other animals, are in- 
jured or destroyed, such animals are then unable to control 
their movements in flying or walking. In certain instances 
of ear-disease in man, similar staggering and falling occur, 
and are supposed to indicate that the semi-circular canals 
are affected. These facts have led to the supposition that 
there resides in these peculiar canals a sense of balance 
of the head and body. However this may be, it is certain 
that they present additional surface for the distribution of 
the auditory nerve. 

7. Sound and its Nature. — Sound is an impression made 
in the ear by the vibrations of elastic bodies, transmitted 
through the air or some other medium. We may compare 
these vibrations to the little waves which ripple the sur- 
face of a pool when a stone has been thrown into it — 
spreading out in every direction from a centre, but grow- 
ing smaller as they recede, till at last they are no longer 
perceptible. 

8. All vibrations do not produce sound ; some are too 
slow to affect the ear, and, on the contrary, others are 



346 ACADEMIC PHYSIOLOGY. 

too rapid. When there are less than 16, or more than 
38,000, vibrations per second, the ear is not affected by 
them. 

9. Sound moves more rapidly in warm air than in cold. 
When the temperature of the air is at 62 , Fahrenheit's 
thermometer, sound travels 1,1 20 feet per second ; and its 
velocity is increased or diminished by the wind, according 
as it blows toward the ear from the sounding body or in 
the opposite direction. While air is not absolutely neces- 
sary to the transmission of sound, sound cannot be pro- 
duced in a vacuum ; and hence it is less intense in rarefied 
air, as upon the tops of lofty mountains. Liquids and 
solids are better conductors of sounds than air ; thus, 
water transmits sound 4^ times as rapidly as air ; iron, 
10 times ; and different kinds of wood, from 1 1 to 17 times 
more rapidly. 

10. Loudness of sound depends on the extent of the vibra- 
tions, or breadth of the sound-waves ; Pitch depends on 
the rapidity of the vibrations — the more rapid, the higher 
the pitch ; Quality of sound depends on the nature of the 
vibrating body. 

11. How we Hear. — When a sound-wave reaches the side 
of the head, part of it is received by the auricle and 
directed into the auditory canal. Flowing on through this 
tube at the rate of 1,120 feet, more or less, per second, 
the waves arrive at the drum-head, beat against it, and 
throw it into a to-and-forth motion. The drum-head im- 
parts its motion to the hammer-bone, and this to the other 
bonelets, causing the entire chain to move back and forth, 
like a pendulum. By this means the foot-plate of the 
stirrup-bone is caused to move in and out with the mem- 
brane of the oval window of the vestibule, compressing 



HEARING. 347 

the liquid contained in it, and setting that in motion. This 
action of the liquid is communicated to the soft parts of 
the labyrinth, in which the nerve lies, and the perception 
of this movement by the nerve-threads of the auditory nerve 
and the brain constitutes hearing. 



CHAPTER XXXVI. 

HYGIENE OF THE EAR AND CARE OF HEARING. 

1. Care of the Auricle. — The auricle should receive moder- 
ate, careful washing with a wash-cloth rather than with a 
sponge. It should be thoroughly dried after washing, for 
any moisture left upon it, upon the prominent bone behind 
it, or in the hair surrounding it, will evaporate and chill 
the ear, cause " cold," and lead to catarrh. After a bath, 
it is the custom of many people, particularly of women, 
to sit in a draught to dry the hair. This practice leads 
to colds, ear-ache, and impaired hearing. A little good 
Castile soap is the safest in washing the auricle — any 
soap that sours should not be used about the ears or else- 
where upon the body. 

2. Suffering from cold ears may be guarded against by 
a light ear-muff, a piece of cotton-wool put lightly in the 
ear, by ear-laps attached to the hat, or by a light woollen 
scarf. The entire ear, however, may be made tender by 
constantly wearing cotton in it while indoors ; and the 
ear-wax may be packed inward and hardness of hearing 
caused by this practice. 

3. A frost-bitten auricle becomes dead-looking and very 
brittle. Care should be taken lest it be broken, and also 



348 ACADEMIC PHYSIOLOGY. 

that warmth be not restored too quickly. If heat be ap- 
plied, intense pain will follow, and inflammation may set 
in — the ear appearing as if burned instead of frozen. 
The circulation of the blood should be restored gradually ; 
and this is done best by rubbing the frost-bitten part with 
snow or ice till feeling is restored, when the auricle is 
safe. 

4. Blows on the auricle may injure the ligaments that 
hold it in place ; and inflammation may extend from these 
to the underlying bone, resulting fatally. 

5. Piercing the auricle for earrings may communicate 
disease from one person to another, unless care is taken 
to thoroughly cleanse the piercing instrument from all 
adhering putrefied matter, after each operation. 

6. Care of the Auditory Canal. — This tube must not be 
obstructed by wax, and yet must be well supplied with it. 
Wax, being necessary to the health of the ear, should not 
be regarded as " dirt," and, as such, constantly scraped 
away. The use of scraping instruments cannot be too 
strongly condemned. They not only pack in as much wax 
as they remove, but also abrade the skin of the canal, 
causing it to become inflamed or to send out moisture 
which putrefies and sometimes induces the growth of 
mould or fungi. 

7. The nse of sweet-oil, glycerine, etc., has a bad effect. 
Sweet-oil, while not having good solvent effect upon 
hardened ear-wax, tends to become rancid when forgotten 
in the ear, and thus, besides increasing pain, provides rich 
soil for the growth of mould. Glycerine has the power 
to dissolve hardened ear-wax, but it has great affinity for 
water, and hence acts like a caustic, burning and stinging 
the ear. It should be mixed with at least eight times its 
quantity of water when used in dissolving ear-wax. 



HEARING. 349 

8. Syringing the ear is the only proper means of cleansing 
the auditory canal ; but neither cold water nor other cold 
liquid should be injected. Warm water, moving easily and 
without jerks, should be used ; the nozzle of the syringe 
being held close to the tube, but not thrust into it. 

9. An insect in the ear-tube may be removed by dropping 
in a little sweet oil, which will either cause the insect to 
crawl out or will smother it, in which latter case syrin- 
ging the canal will float the intruder out. 

10. A hard foreign body in the ear-tube may usually be 
removed most easily and successfully by forcing it out 
gently by syringing. In case, however, the object in the 
ear is a bean, a pea, or a corn grain, etc., too long con- 
tinued use of the syringe would soften and swell it, thus 
delaying its removal. 

11. Do not probe the ear to remove objects from it. If a 
foreign body cannot be removed by syringing, you may 
be assured that it will not pass beyond the reach of the 
surgeon's skill. It cannot reach the brain, or even the 
middle ear, unless you push it in through the drum-head. 
Let it alone — the skill of the surgeon is now required in 
its removal. 

12. Care of the Drum-Head. — In swimming or diving — 
particularly, the latter — cotton should be placed in the 
ear-tube to prevent the entrance of cold water, and conse- 
quent inflammation of the drum-head. 

13. Bathing in the sea and smf has dangers for the ear. 
The direct force of the waves dashing into the ear has 
caused the rupture of the drum-head and produced per- 
manently defective hearing. Besides, the coldness and 
stimulating nature of sea-water irritate the canal and 
drum-head. In sea-bathing the ear should be protected 
by cotton. 



350 ACADEMIC PHYSIOLOGY. 

14. "Boxing the ears" and concussions from unexpected 
explosions, are common sources of injury to the drum-head. 
These coming suddenly, the membrane is not prepared to 
resist ; and if the Eustachian tube is temporarily closed 
at the time, rupture of the drum-head is probable. Open- 
ing the mouth when an explosion is expected, for reasons 
already explained, relieves the drum-head from much of the 
concussion. When a rupture of the drum-head is either 
suspected or known, put nothing into the ear. Any liq- 
uid put into the canal would pass through the fissure in 
the drum-head into the drum-cavity, and thus cause inflam- 
mation. Instead, put a little dry cotton in the entrance 
of the canal, and usually the ruptured drum-head will heal. 
Any force sufficient to rupture the drum-head may, by 
concussion, injure the deeper and still more delicate por- 
tions of the ear, causing permanent deafness. A severe 
blow or a fall upon the head may be the cause of deaf- 
dumbness in a child if the injury occurs before he has 
learned to talk. 

15. Shouting loudly and suddenly into a person 's ear is 
an ignorant or vicious trick ; besides the shock to the 
nervous system, which is sometimes disastrous, it may 
result in permanent deafness. The trick is too dangerous 
to be tolerated. 

16. The noise of boiler-making and loud clatter of ma- 
chinery affect the ear badly. The constant and severe shock 
of these noises finally exhausts the nerve-power. Much of 
the bad effect may be guarded against by wearing some-' 
thing over the ear while it is exposed to them. 

17. Care of the Eustachian Tube. — All possible care must 
be taken to keep this tube free from obstructioit if hearing is 
to remain perfect. If, after a cold in the head or a sore 



HEARING. 351 

throat, the tube is allowed to remain closed, it may, 
through inactivity, become entirely unable to open and 
admit air into the drum. A vacuum is thus created, the 
drum-head falls inward, the entire hearing apparatus is 
thrown out of order, and deafness sets in. 

18. Breathing through the mouth is injurious to the throat 
and to hearing. Mouth-breathing, which is most frequently 
occasioned by allowing the nostrils to remain clogged with 
mucus, causes the mouth and throat to become dry, and 
the Eustachian tube to become irritated and closed. 

19. Catarrh snuffs, and liquids for snuffing into the nos- 
trils, produce ear-diseases. These preparations are some- 
times drawn directly into the Eustachian tube, clog it, or 
cause inflammation in the drum-cavity. 

20. Effects of Alcoholic Drinks and Tobacco on the Ear. — 
The use of much alcoholic drink injures the ear, directly, 
in at least two ways: 1st, by inflaming the throat, and, 
by that means, the Eustachian tube and middle ear ; 2d, 
by congesting the blood-vessels of the internal ear. To 
these may be added its bad effects upon the nervous sys- 
tem, of which the nerve of hearing forms a part. 

21. The use of tobacco, in all its forms, is severely and 
generally condemned by aurists. — Chewing is apt to cause 
catarrh of the throat ; and snuffing, catarrh of the nose 
— each thus tending to induce ear-disease and impaired 
hearing. Tobacco smoke, especially when blown through 
the nostrils, is brought directly to the mouth of the 
Eustachian tube, and may produce inflammation there ; 
hence, the smoking of cigarettes is supposed to be more 
especially harmful. The atmosphere of a smoke-filled 
room is irritating to the nose and throat, and therefore to 
the ear. 



352 ACADEMIC PHYSIOLOGY. 



CHAPTER XXXVII. 

TASTE AND SMELL. 

1. Taste and Smell Compared. — In many respects taste and 
smell are twin senses. Among the substances which we 
taste, there are few that address themselves solely to that 
sense, and not at the same time to the sense of smell. 
Flavors and odors are so mingled together in the same 
substance, and the action of the senses which perceive 
them so nearly simultaneous, as to induce some authori- 
ties to consider them as one. They are, however, quite 
distinct in their location and in several important func- 
tions ; the mixed sensations resulting from the union of 
the impressions of taste and smell are quite different from 
those caused by each separately. It may therefore be 
said that the sense of smell is the necessary complement 
of the sense of taste, as the latter becomes very much 
weakened and less in importance when deprived of the 
assistance of the former. 

2. These senses aid in the determination of what is 
pleasant or disagreeable, wholesome or unwholesome, to 
the system in general. The location of the organs at the 
entrance to the digestive and respiratory cavities of the 
body suggests that they are sentinels to warn us in 
regard to the character of substances brought into con- 
tact with them, and thus to afford the reason and the 
judgment opportunity to decide whether they are good 



TASTE. 353 

or bad, innocent or harmful. It is true that we are fre- 
quently deceived by these senses in regard to the whole- 
someness of substances with which we have not become 
familiar through experience. Many baneful matters are 
pleasant to taste and to smell ; and this fact proves that 
our reason and judgment are to be employed as correctors 
of our senses, and that the latter are not to be trusted 
alone. 

3. The brute creation, which depends more fully upon 
animal instinct, have all the special senses strongly de- 
veloped and correspondingly acute. 

4. The Organs of Taste. — Physiologists do not all agree 
in locating the portions of the tongue and mouth that are 
sensitive to taste. Some believe that the seat of taste 
extends over nearly the whole surface of the tongue, to 
the fauces, to the upper surface of the soft palate, and 
to the pharynx. The belief is quite general, however, that 
it is located at the tip, sides, and base of the tongue, and 
on the front surface of the soft palate, to all of which 
branches of cranial nerves are supplied. 

5. The tongue not only participates, by its movements, 
in the digestive process and in the articulation of sounds, 
but its special sensibility constitutes it also the principal 
organ of taste. It is a muscular organ covered with 
mucous membrane. Its upper surface is rendered rough 
by numerous small conical elevations called papillce, all 
of which are richly supplied with blood-vessels and nerves. 
Those at the root of the tongue are large, and are 
arranged in two oblique rows forming a V-shaped figure, 
with the angle directed backward ; those at the tip and 
edges of the tongue are smaller and more numerous. 

6. It appears that, in order to produce the sensation of 



354 ACADEMIC PHYSIOLOGY. 

taste, the particles of substances must be brought into 
actual contact with the nerve-fibres in the papillae by 
penetrating the outer layer of mucous membrane which 
covers them. It is therefore necessary that substances to 
be tasted must either be already in solution, or must be 
capable of being dissolved by the saliva of the mouth, in 
order that they may easily penetrate to the terminations 
of the nerves of taste. Dry substances, or those inca- 
pable of being dissolved, do not produce a sensation of 
taste. The salivary glands supply all the moisture that is 
ordinarily required to moisten food and bring out its 
flavor; but during fevers the supply of saliva is lessened, 
the mouth becomes dry, and the pleasurable sense of taste 
is almost wholly lost. 

7. Curiosities of Taste. — The nerve-fibres of the tongue 
and palate are derived from two sources, one 1 of which 
supplies the middle and tip of the tongue, the other 2 its 
back and the adjacent parts of the palate, etc. There is 
reason to believe that both these nerves are nerves of 
taste, although they are not precisely similar in their 
functions. Sweet and salt tastes are perceived more 
readily at the tip than at the back of the tongue. Sugar 
may be placed on the back of the tongue without produ- 
cing any sensation of taste. Bitter flavors are soonest 
detected when applied to the back part of the tongue, and 
acids when applied to its edges. 

8. A very large number of the sensations which we call 
taste are not simple, but complex, in which smell, and even 
touch, are factors. Smell is so closely related to taste 
that the odor of a substance often suggests its taste. 
When the sense of smell is obstructed, as when the nos- 

1 The glassopharyngeal nerve. 2 The gustatory nerve. 



SMELL. 355 

trils are pressed together, or during a severe cold, or when 
it has been destroyed by catarrh, it is either difficult or im- 
possible to distinguish the flavors of different substances. 
The eyes being closed, the taste of an onion may then be 
mistaken for that of an apple, and vice versa. In this we 
find an explanation of the common practice of closing the 
nostrils while a dose of nauseous medicine is being taken. 
9. As it is not the eye that sees, nor the ear that hears, 
neither is it the tongue that tastes. Impressions made on 
the nerves of taste are conducted by them to the brain, 
where they are recognized. 



10. The Sense of Smell. — The sense whereby we become 
cognizant of odors contributes greatly toward the pleasures 
of life, and it not infrequently warns us of the presence of 
noxious gases which might destroy it. Placed directly 
over the mouth, its organs examine the substances which 
are presented for admission into that cavity, and primarily 
discriminate as to their fitness. Furthermore, as the 
passages of the nose are important avenues to the lungs, 
entering air must undergo an examination by the organs 
of this sense, and its fitness for the purposes of respira- 
tion be subject to their verdict, or rather to that of the 
brain to which they conduct the sensation. Thus it is 
seen that under the protecting guidance of this sense, 
supplemented always by reason and judgment, injury to 
the body and its health may be avoided. 

11. The lower animals depend wholly upon this sense as 
their guide to proper food, and as a protector from that 
which is liable to be harmful. To them it is still more 
important than to man, and its acuteness is proportionate 
to its necessity. 



356 ACADEMIC PHYSIOLOGY. 

12. The Organ of Smell. — The seat of the sensation of 
smell is in the mucous membrane which lines the cavities 
of the nose. The nerves which are specially devoted to 
this sense are called the olfactory nerves (Lat. olfactus, the 
smell). These nerves, one on each side, separate into an 
immense number of minute filaments immediately before 
passing out from the cranial cavity, and each filament 
passes through a separate little hole in a very thin plate 
of bone situated immediately over the top of the nasal 
cavity, between the orbits of the eyes. This delicate, 
bony plate alone separates, in this region, the brain from 
the cavity of the nose ; the great number of its perfora- 
tions give it a sieve-like appearance, and hence it is tech- 
nically called the cribriform plate (Lat. cribrum, a sieve). 
Having entered the cavity of the nose, the innumerable 
nerve filaments ramify in portions of the mucous mem- 
brane which lines it. 

13. The two irregular air passages leading into the 
more remote cavities of the nose are separated by a parti- 
tion l of bone and cartilage. The bones at the sides of 
these passages curve in a scroll-like form, and are covered 
with a very delicate kind of membrane, containing mucous 
glands which secrete a fluid that moistens it and is of im- 
portance in completing the impression of smell. The 
cavities extend up to the point where the nose joins the 
forehead, and backward and downward they are continu- 
ous with the cavity of the pharynx. The irregular form of 
the bones, and the winding nature of the cavity of the nose, 
increase the surface for the distribution of the branches 
of the nerves of smell. 

14. The organ of smell being thus constituted, particles 

1 The septum. 



SMELL. 357 

given off from odorous substances are carried by the air 
which is drawn in through the nose and brought into con- 
tact with the membrane and filaments of the nerves of 
smell. This process is facilitated by the moisture of the 
membrane, which causes the odorous particles to adhere 
and be retained, thus giving them opportunity to make a 
more distinct impression on the nerves. The various im- 
pressions are conducted by the olfactory nerves to the 
brain, where they are converted into the sensations known 
as smell, or the sense of odor. How the brain recognizes 
odor, or how it distinguishes different odors, is not known. 
It may be that different odorous substances give rise to 
different changes in the nerve cells, each distinctive of the 
odor that causes it ; or it may be that certain cells of the 
brain are adapted to especially recognize impressions 
made by different particles. 

15. When it is desirable to be exact in perceiving an odor, 
the mouth is closed, and sudden, short inspirations are 
taken wholly through the nose. This causes upward and 
sudden rushes of air into the nasal cavities, and disturbs 
the comparatively still air which Ts enclosed by the folds 
of the scroll-like bones, causing some of it to give place to 
the in-coming air laden with the odorous particles that 
would not otherwise come in contact with the termina- 
tions of the nerves of smell. This practice of sniffing the 
air to detect odors is common to man and the lower ani- 
mals, especially to the latter. 

16. Curiosities of the Sense of Smell. — The sense of smell 
can be cultivated to a certain degree. A nice discrimina- 
tion between odors can be attained by practice and obser- 
vation. It is the education and training of the senses 
that make the judgment of some persons better than that 



358 ACADEMIC PHYSIOLOGY. 

of others in regard to the conditions of material things. 
A trained eye can see beauties and defects ; a trained ear 
can detect harmonies and discords ; and trained senses of 
taste and of smell detect flavors and odors that escape 
observation when these senses are not educated. 

17. Simple experiments prove that odorous substances 
emit invisible streams of particles so small as to seem to 
be immaterial ; and nothing gives a more exact idea of the 
divisibility of matter than the diffusion of odors. Half 
of a grain of musk placed in a room will diffuse its parti- 
cles throughout the entire space and produce a strong 
odor for a long time, without apparent diminution of its 
bulk or weight. 

18. " Heat, light, and other influences modify the pro- 
duction of odors and their transmission in space. Certain 
plants are odorous only at night ; and it is especially in 
the morning and evening, when the dew is scanty, that 
flower-gardens perfume the atmosphere. Rain destroys 
the perfume of flowers, probably by its mechanical action, 
and by lowering their temperature. It is remarkable also 
that animal or vegetable* odors are feeble as the countries 
are colder in which the animals or plants live from which 
they emanate. Hence perfumes come principally from 
tropical countries." 

19. Curious phenomena are exhibited by the sense of 
smell. Some persons faint on smelling a particular odor, 
that of a rose for instance, and there is no doubt that cer- 
tain odors may cause grave disturbance in the nervous 
system ; but people often ascribe to odors effects which 
are really produced by carbonic acid gas, or other poison- 
ous emanations, absorbed by the lungs. 

20. The proverb which states that " there is no 



touch. 359 

accounting for taste " applies in the case of fondness for 
certain odors. Individuals and nations differ singularly 
in this respect. The Laplander and the Esquimau find 
delight in the odor of fish-oil, and there are persons who 
do not find the odor of assafoetida more disagreeable than 
that of the attar of roses. No doubt familiarity with 
certain odors, that are at first highly repulsive to the great 
majority of people, causes them to become not only tol- 
erable, but pleasurable to the sense of smell in some 
individuals. 

21. The sensations of smell and taste are easily con- 
fused, one with another. Again, owing to the persistence 
of the sensations, we cannot discriminate two odors or 
two tastes when one follows the other in rapid succes- 
sion, as we can a number of simultaneous touches locally 
separate from each other. 



CHAPTER XXXVIII. 

TOUCH. 

1. Touch as a Sensation. — The sense of touch is some- 
times classed among the general sensations, because it is 
so closely related to feeling and pain, and is so widely 
distributed. But we must discriminate between the sense 
of touch and the sensation of feeling and of pain : touch 
proper is a sensation by which we gain knowledge through 
contact with objects in the material world, while feeling 
or pain may either accompany the pure sense of contact, 
or exist without it, and simply make us aware of certain 



360 ACADEMIC PHYSIOLOGY. 

conditions of various parts of the body. Touch may there- 
fore be regarded as a modification of the common sensa- 
tion of feeling, whereby the contact of any object with a 
sensitive portion of the body reveals its form, hardness, 
and temperature. Thus feeling or pain may exist without 
sense of contact or touch. Feeling may be involuntary, 
while touch is an act of the will ; there is, therefore, the 
same difference between feeling and touch that there 
is between seeing and looking, or between hearing and 
listening. 

2. To the sense of touch or contact we owe immunity 
from dangers which often escape the observation of the 
sense of sight ; so delicately sensitive are many portions 
of the body that the movement of the slightest breeze, or 
the contact of the lightest feather, is instantly perceived, 
and the attention is drawn to the precise point of touch. 

3. The Organ of Touch. — The nerves of touch are located 
in the skin throughout its whole extent, and in some of 
the mucous membranes. Wherever the sense of touch is 
most delicate, the deep layer of the skin is raised up into 
multitudes of small conical elevations called papillae. In 
many of these the nerve-fibres end in a tactile corpuscle 
(see Chapter XXVIII., "Nerves of the Skin"). These 
bodies are especially found in the papillae of those localities 
which possess a very delicate sense of touch, as in the tips 
of the fingers, the point of the tongue, etc. The outer skin 
covers these papillae, but dips down between them, and 
hence no direct contact takes place between an object 
which is touched and the sensory nerve itself. Slight 
pressure upon the outer skin creates the impression upon 
the nerve filaments beneath it. The sensitiveness to 
touch of any part is proportionate to the number of its 



TOUCH. 361 

papillae and the variable thickness of the outer layer of 
the skin. 

4. But all sensations produced by the contact of the 
skin, etc., with objects are not alike. Combined with the 
sense of touch, there are frequent sensations of feeling, 
as of pain, temperature, etc. These varied sensations are 
difficult of explanation. The feeling of warmth or of 
cold is the result of impressions made upon sensory 
nerves which are possibly distinct from those which 
simply give rise to the sense of touch. In some way the 
nerve-twigs which end in the papillae possess the power 
of discrimination, and the information which they con- 
duct to the brain is there utilized in directing our actions 
amidst the material forces of the world. 

5. Curiosities of the Sense of Touch. — Certain phenomena 
which appertain to the sense of touch are very curious 
and interesting. Some of these peculiarities are undoubt- 
edly due, in part, to the varying thickness of the epidermis, 
and to the abundance or the scantiness of the distribution 
of the special nerve-fibres. 

6. When the two ends of the legs of a compass are 
applied simultaneously to the skin, they must be more or 
less separated, according to the region experimented on, 
in order that their contact may cause two distinct sensa- 
tions of contact, instead of but one. Thus, if the points 
are separated only one-twelfth of an inch and applied to 
the tips of the fingers, two distinct impressions of touch 
are produced, whereas if applied to the back of the hand 
in the same way, but one impression is perceived ; on the 
arm the points may be separated one-fourth of an inch, 
on the cheek an inch, and on the back even three inches, 
and still give rise to only one sensation. The tip of the 



362 ACADEMIC PHYSIOLOGY. 

tongue, on the contrary, receives two impressions when 
the points are separated only one-twenty-fourth of an 
inch. In this way the degree of sensitiveness to touch 
possessed by the skin of different regions of the body 
may be measured by its power of distinguishing between 
two or more impressions at points very near each other. 

7. The idea of external objects given by touch often 
depends upon the possibility of distinguishing the differ- 
ent parts of a body as occupying different places in space. 
If, for example, a small sphere is caused to revolve be- 
tween two parallel fingers of the same hand, the impres- 
sion produced is that of a single body touching both 
fingers ; but if the fingers are crossed, and the ball placed 
between their extremities, the impression produced is that 
of two balls, each rolling in contact with one of the 
fingers. 

8. Contact with the same body may produce successive 
impressions of heat or of cold without a change in its 
temperature, depending respectively upon the coldness or 
warmth of the surface of the skin at the moment of con- 
tact. Thus, in placing a cold hand upon any portion of 
the body that retains a normal temperature, that portion 
appears to be unusually warm ; but if the hand is nor- 
mally warm, the part on which it is placed seems to be 
much cooler than in the first instance. Again, if a bath 
is taken in water cooler than the air, the temperature of 
the air, which seemed low on entering the bath, seems 
warmer on leaving the bath a few minutes afterward. 
For the same reason the air of a cellar appears cooler 
in summer and warmer in winter, although it has not 
varied. 

9. Of two different bodies having the same temper- 



TOUCH. 363 

ature, one may seem much colder than the other when 
brought into contact with the skin. Thus, iron appears 
colder than wood, and water colder than air, at the same 
temperature. In such instances, the sensation of temper- 
ature is strong in proportion to the conducting power of 
the object in contact with the skin. 

10. Unaided by the sense of sight, it is difficult or im- 
possible to distinguish between the sensation produced by 
an object at a very low temperature and that by one at a 
high temperature. Contact with the point of an icicle is 
readily mistaken for contact with a hot iron, and contact 
with a ball of frozen mercury ( — 40 Fahrenheit) causes 
a burning sensation, the same as that of iron heated to 
212 Fahrenheit. 

11. The hand is naturally the principal instrument for 
exercising the touch, and it becomes rapidly inured to 
contact with objects that are so hot as to cause pain to 
those unaccustomed to such contact. The membranes 
of the tongue, mouth, and throat, in persons of mature 
age, often bear, without pain, the contact of food and 
drink so hot that younger people could not tolerate them. 

12. From the foregoing illustrations it is evident that 
the sense of touch is not a reliable thermometer ; and 
that while it cannot replace the other senses, it frequently 
corrects their impressions. When we permit its full de- 
velopment, and employ it with the reason and judgment 
which result from a co-ordination of sensations, it is suffi- 
cient to guide us in matters of health related to external 
objects. 

13. Delicacy of Touch. — Through cultivation and exer- 
cise, touch attains extreme delicacy. The necessities of 
the blind result in a cultivation of this sense whereby 



364 ACADEMIC PHYSIOLOGY. 

wonderful facility is acquired in various delicate manipu- 
lations ; and persons in various occupations in which great 
sensitiveness and delicacy of touch are required, attain 
these in a remarkable degree. 

14. Diseases of the nervous system often intensify sen- 
sibility to touch ; and, on the other hand, disease some- 
times modifies, suspends, or destroys it. In this respect, 
like the other senses, it is dependent upon conditions 
which affect the great nerve system, as well as upon local 
disease of its organs. 

15. The Voice. — The organ of voice is the larynx (see 
Fig. 37), which is a modification of the upper portion of 
the trachea. It consists of a cartilaginous framework, the 
parts of which are movable on each other by means of 
the contraction of muscles. The upper end of the larynx 
is nearly closed by two bands of membrane (the so-called 
vocal cords), between which a narrow slit or chink (the 
glottis) is left for the passage of air. The epiglottis, 
which is not employed in the production of sound, is a lid 
of cartilage which closes the space between the cords 
during the act of swallowing. 

16. During quiet breathing the vocal cords are relaxed ; 
but when we wish to speak, sing, etc., certain muscles 
stretch the cords more or less, and narrow the opening ; 
and when the air is forced out with sufficient velocity, the 
cords are caused to vibrate, and sound is produced, — the 
more rapid the vibration the higher the pitch. In sing- 
ing, 128 vibrations per second produce the bass C ; 256 
the tenor C ; and 512 the treble C. "The power which 
the will possesses of determining the exact degree of ten- 
sion which these cords shall receive is extremely remark- 
able. . . . There must be at least 240 different states of 



EFFECTS OF ALCOHOL AND TOBACCO. 365 

tension, every one of which can be determined by the 
will ; and the variation in length required to pass from 
one musical ' interval ' to another will not be more than 
T2W of an inch." 

17. On account of the greater length of the vocal cords, 
the pitch of the voice in men is much lower than in women ; 
but this difference does not occur until the end of the 
period of childhood, — the size of the larynx being about 
the same in the boy and girl up to the age of fourteen or 
fifteen years, but then undergoing a rapid increase in the 
former, with a corresponding depth of tone, whilst it 
remains nearly stationary in the latter. 

18. Effects of Alcohol and Tobacco. — As both alcohol and 
tobacco are injurious to the nervous system, they are con- 
sequently harmful to the organs of the special senses, one 
or all of which are more or less impaired by these nar- 
cotics. 

19. Smoking often causes dilation of the pupil of the 
eye, confusion of sight, bright lines, cobweb specks, etc. 
Oculists are of the opinion that one of the greatest ene- 
mies of the eyes of boys and young men is the cigarette, 
the smoking of which is especially harmful in various 
ways. More of the hot soot-laden smoke is drawn into 
the air-passages, and more of the acids and alkalies come 
in contact with the delicate linings of these, and are ab- 
sorbed into the blood, than in pipe or cigar smoking. 
Deaths among the young caused by cigarette smoking are 
frequently reported, and undoubtedly many more occur 
from this cause than are publicly made known. 

20. Alcohol and tobacco when habitually used benumb 
the nerves of taste, causing them to be incapable of detect- 

1 Carpenter. 



366 ACADEMIC PHYSIOLOGY. 

ing delicate flavors ; and hence, plain food becomes in- 
sipid. Resort is then had to highly seasoned food as a 
spur to the taste. The smoke of tobacco contains many 
fine particles which find lodgement in the mucous lining 
of the passages of the nose, causing inflammation and im- 
pairment of the sense of smell ; or, by inducing or aggra- 
vating catarrh, sometimes destroying the sense of odor 
entirely.- Even the sense of touch is rendered less delicate 
by these agents which act so powerfully on the nerves. 



Suggested Points for Questions. 

Chapter XXXII. — 1-3. Sensation in general — knowledge obtained 
through sensation. General sensation defined — examples; character of 
knowledge thus obtained. Muscular sense — object and peculiarities. 4. 
Special sensations — whence they arise; stimulus applied to a definite organ 
— local character; illustrations of; sense organ defined; external objects or 
causes — basis; special senses named. 5. Sense of sight — importance, 
functions; sadness of deprivation; sight and touch related. 6-8. Anatomy 
of eye — location; eyeball — form and protection; eyelids and lashes — func- 
tions; eyebrows; tear-gland — secretion and function; nerves, blood-vessels; 
muscles and their importance to sight — effect of undue contraction or relax- 
ation. Size and form of eyeball — elongation; coats or tunics; refracting 
mediums; optical instrument. 9-14. Coats, humors, lenses, etc. — sclerotic 
coat described and functions stated ; the cornea described — window. Choroid 
coat — location, nature, blood supply, pigment cells, principal function — 
darkening. The iris — location and general structure — aperture, muscular 
action, contraction of pupil and why; color of eye — source. The retina — 
location, structure (an expansion of optic nerve), function — receives impres- 
sions. Crystalline lens — location, form, size, transparency, capsule and 
ligament; change of position and curvature — object; office of lens. Spaces 
or cavities occupied; aqueous and vitreous humors — location, characteristics, 
and functions of each. 15-17. Appendages — conjunctiva, nature, location, 
and glands of — functions. Lachrymal gland — location, size, secretion, 
ducts, distribution of fluid, lachrymal and nasal ducts — location and office; 



SUGGESTED POINTS FOR QUESTIONS. 367 

obstruction of ducts — effect ; office of tears. 18-21. The phenomena of 
sight — sight the result of various agencies; necessity of light; light-waves 
and variation in length — effects; visual sensation defined; visual judgment 
defined. Sensation of light lasting —illustration. Degree of intensity de- 
pendent on brightness — limitation. Phenomena explained by physics — some 
little understood. 22-26. Visual sensation — reception and passage of light 
through the eye; convergence and focus; inverted image; impression on optic 
nerve; recognition by brain — visual judgment. Contraction of pupil, change 
of shape of lens — acts of accommodation; causes of contraction of pupil. 
Sensitiveness of retina — variation in parts; "yellow spot" and its phe- 
nomena; axis of vision. " Blind spot " — location, phenomena, experiment. 
Exhausted retina — cause and phenomena. 27-29 Normal sight — nearness 
of object in vision — when indistinct and to what due; range in reading or 
writing; adjustment for distant vision. Near-sightedness — nearness of object 
required ; causes of near-sightedness — convexity, elongation, focusing. 
Relief by "glasses." Far-sight — peculiarities; inherited and from age; 
changes of form of eyeball and lens in far-sight — effect on focal distance; 
convex glasses for relief; near and far sight in same person — glasses. 30- 
34. Recognition of color — charm of color. Sunlight white; spectrum colors 
— blending and shades. Color of objects due to what — effect on retina. 
Color-blindness — peculiarities, probable cause; unfortunate but dangerous — 
reason. 35-39. Visual judgments — definition; an infant's impressions — 
visual perception not judgment. Process of gaining visual judgment — asso- 
ciation of senses, experience, etc. Agency of touch and repetition — result. 
Vision with both eyes — resultant image on retinas differ; combination of 
images — solidity impressed; stereoscope — analogy. Relation of retinal 
impression to brain recognition — mystery. 40. Optical delusions — origin 
from complex combinations and sensations, etc.; not necessarily nervous 
derangement — comment. 

Chap. XXXIII. — 1. Essentials of perfect sight — perfect condition and 
correct position of parts; conditions, etc., requisite in cornea, humors — iris, 
pupil, lens, retina, pigment of choroid, optic nerve. 2-15. Care of the eyes 
— over-taxing under bad conditions; inheritance versus carelessness; com- 
mon abuses of the eyes mentioned. Position of body in relation to light; 
employment of shades; position of school desks — importance. Manner of 
holding and position of book in reading — reason; inclining the head — con- 
gestion. Deficient and irregular light — effect. Fine work and resting of 
eye — method and when. Cleanliness of hands and why; towels and sore 
eyes — caution. Cinders, dust, etc., in eye — rubbing avoided, agency of 
tears in removal; methods of removing foreign body from eye, A particle 



368 ACADEMIC PHYSIOLOGY. 

imbedded in eyeball — treatment. Lime in the eye — treatment. Exclusion 
of light and light bandaging — when; delay dangerous. Reading while 
lying — injurious and why. Cleanliness of eye and appendages — means. 
When to consult oculist — reason. Care in general hygienic matters, etc. — 
advice of an eminent oculist. 16-18. Defects requiring glasses — dangers of 
neglected defect, tendency to increase; defective sight —when first experi- 
enced. Selection of glasses — when prudence demands use of, by whom and 
why; when to use in daylight — limitation; use of single glass — injurious; 
use in far-sight — caution; properties of first glasses used. Normal failure of 
good sight — when and variation. 

Chap. XXXIV. — 1,2. Location of the ear — a complicated organ; loca- 
tion of delicate parts; an element of physiognomy — expression. Difficulty of 
investigation — why; divisions or regions of ear named. 3. Divisions of 
external ear. 4. Auricle — form, peculiarities, functions in relation to 
sounds; hair of auricle — function. 5-8. Auditory canal — acoustic tube; 
dimensions and closure. Ear-wax glands — location, number, secretion, im- 
portance of. Casting out of surplus wax — conformation of canal and pro- 
cess of expulsion of wax and dirt. 9, 10. Tympanic membrane — location, 
form, size, layers, attachment. Functions described — action of air-waves 
communicated to auditory bones. II. Middle ear — location, form, occu- 
pants of; divisions and adjuncts. 12-14. Tympanum or drum — size of 
cavity; lining and delicacy; the drum proper; most liable to disease. 13, 14. 
The ossicles or auditory bones — number, form, sizes, names, connection in 
chain, attachment to drum-head and to membrane in inner ear, vibration 
communicated by — process and impression. 15-18. Eustachian tube — an 
air-tube, location, length, openings; opened by swallowing, and air enters 
— result and analogy; result of closure of tube — effect on drum-head; com- 
pressed by yawning — effect. Blows on ear or explosions — effect in tube 
and good result; gunners^ and opening of mouth in firing — why. 19, 20. 
Mastoid cells — location and structure; air-chambers — connections; func- 
tions. Thinness of boundary wall — liability to participate in disease of drum 
cavity. 

Chap. XXXV. — 1 The internal ear or labyrinth — complicated nature, 
functions in part uncertain; central cavity, spiral tubes, winding channels — 
filled with water; filaments of auditory nerve — distribution; general function; 
divisions named. 2. Vestibule — location, form; communication with drum- 
cavity; oval and round windows — membranes of; and connection made with. 
3, 4. Cochlea — form; spiral passages. Distribution of nerve in — harp- 
like; probable functions — musical sounds. 5, 6. Semi-circular canals — 
number, form, enlargement; effect of injury of in animals; disease of in man 



SUGGESTED POINTS FOR QUESTIONS. 369 

— indication and conclusion as to function ; afford additional surface for 
nerve. 7-10. Nature of sound — sound defined — analogy to wave-circles. 
Soundless vibration — too slow, too rapid; number of soundless per second. 
Sound affected by temperature, by wind, by vacuum, by rarefied air; liquids 
and solids as conductors — speed. Loudness, pitch, quality — dependence. 
11. How we hear — mechanical action stated; perception of movement. 

Chap. XXXVI. — 1-5. Care of auricle — careful washing, drying — rea- 
son; drying in a draught — error; kind of soap. Suffering from cold ears — 
protection; cotton worn in ear — effect. Frost-bitten ear — care and treat- 
ment. Blows — possible effect. Piercing — disease communicated. 6-1 1. 
Care of auditory canal — improper means of removing obstruction — wax, 
etc. Use of sweet-oil, etc. — effect and why. Syringing as a means of 
cleansing — method and conditions. Insect in ear removed — method. Hard 
foreign body in ear-tube — method of removal and exception. Probing as 
means of removal — objectionable. 12-16. Care of drum-head — in swim- 
ming or diving; in sea- or surf-bathing; danger from boxing the ear and from 
explosions — explanations; treatment in case of ruptured membrane; deaf- 
dumbness from blow on head of child. Shouting in ear — why improper. Noise 
of boiler-making, etc. — effect and protection. 17-19. Care of Eustachian 
tube — unobstructed for perfect hearing — effect of cold. Mouth-breathing 
injurious — why. Catarrh snuffs and liquids — injury by. 20,21. Alcohol, 
tobacco, and hearing — inflame throat, Eustachian tube, and hence, ear; con- 
gest blood-vessels in ear; injury to auditory nerve. Use of tobacco — 
catarrh of throat and nose, injury extending to ear; smoke inflames 
tube; cigarette — why specially harmful; atmosphere of a smoke-filled 
room — reason. 

Chap. XXXVII. — 1-3. Taste and smell compared — flavors and odors 
simultaneous; nature of mixed sensation; smell the complement of taste. 
Functions of taste and smell; location of the organs suggestive. Deception by 
these senses — reason and judgment correctors. Brutes — keenness of special 
senses and why. 4-6. Organ of taste — beliefs regarding seat of taste in<the 
tongue, etc., and parts concerned; tongue the principal organ of taste — other 
functions; structure of tongue — papillae, vessels, nerves; arrangement of 
papillae. Process of taste — contact, moisture, solution; dry substances and 
taste; office of the saliva, loss of taste in fever — why. 7-9. Curiosities of 
taste — two sources of nerve-fibres — distribution of, in tongue, and belief con- 
cerning function; sweet and salt tastes — perceived where; sugar and back 
of tongue; bitter flavors — where; acids. Complex sensations of taste and 
smell — odor suggests taste; taste feeble when smell is obstructed — in- 
stances; sensation recognized by brain. 10, 1 1. Sense of smell — contributory 



3?0 ACADEMIC PHYSIOLOGY. 

to pleasure and protective ; entering air examined and verdict rendered. 
Keen smell in lower animals — guide, protection. 12-15. Organ of smell — 
seat of sensation — nasal cavities; olfactory nerves of mucous membrane — 
distribution of filaments through cribriform plate described; separation of air- 
passages — septum ; mucuous glands and function ; extent of cavity and 
olfactory surface; process of smelling — odorous particles, contact, moisture, 
result; theory of different sensation of odor. Sniffing to perceive exact odor 
— philosophy of. 15-21. Curiosities of smell — cultivation and education of 
the sense — result. Streams of odorous particles emitted — instance. Pro- 
duction and transmission — modifying agents; odorous plants — morning, 
evening, dew, rain, cold. Fainting from odors — nervous disturbance; singu- 
larity in liking for odors — fish-oil, etc., enjoyed; familiarity with repulsive 
odor — result. Taste and smell confused; difficulty in discriminating too 
closely following odors or tastes. 

Chap. XXXVIII. — 1, 2. Touch as a sensation — relation to feeling and 
pain — discrimination. Touch defined. Immunity from danger afforded; 
delicacy of the sense. 3,4. Organ of touch — nerves in skin; papillae; tactile 
corpuscles, where numerous; no direct contact with nerve — skin covering; 
sensitiveness to touch — dependent on what. Touch mingled with sense of 
pain, temperature, etc. — possible explanation of nerve-action. 5-12. Curi- 
osities of touch — peculiarities due to what. Experiments with pointed legs 
of compass — single or double impression of contact in various regions of 
skin; deduction as to sensitiveness. Contact of crossed fingers with a small 
sphere — impression and possibility of distinguishing. Contact and successive 
impression of heat and cold without change of temperature — instances and 
philosophy. Different bodies of same temperature — one feeling colder than 
other and why. Very high and very low temperature — similarity of sensa- 
tion of contact, and instance. The hand as an instrument of touch — inured 
to heat; membranes of mouth, tongue, etc., and hot food. Touch not a 
reliable thermometer; correction of impressions by; co-ordination of sensa- 
tion. 13, 14. Delicacy of touch — results of cultivation; in the blind; in 
various occupations. Disease as related to sense of touch — intensify, modify, 
destroy. 



EMERGENCIES. 



CHAPTER XXXIX. 

EMERGENCIES, OR FIRST AID TO THE INJURED. 

1. Poisoning. — As a rule, cases of poisoning in which 
home treatment can be employed with advantage are those 
in which the kind of poison taken is known. All cases of 
poisoning are serious, and immediate treatment may save 
life ; but a physician should also be summoned at once. 

2. In all cases of poisoning an emetic should be admin- 
istered as soon as possible, except where the poison itself 
produces vomiting. A table-spoonful of mustard or salt 
in a cupful of hot water will often serve the purpose. 
Tickling the throat with a feather will further assist. 

3. Chemical antidotes to the action of poisons require 
the exercise of memory and of knowledge. Acid poisons 
are antidoted by alkalies, and the most convenient forms 
of the latter are chalk, lime, and magnesia. On the other 
hand, caustic alkalies are neutralized by acids, and hence 
vinegar, lemon-juice, etc., will be found most convenient 
in an emergency. 

4. Arsenic is a common form of poison, and is a prin- 
cipal constituent of rat and insect powders, or mixtures 
for killing vermin. It produces faintness, nausea, vomit- 

37i 



IJ2 ACADEMIC PHYSIOLOGY. 

ingy and depression within an hour after it is swallowed. 
Intense thirst, burning pains in the stomach, violent 
cramps of the abdomen and legs, and cold, clammy skin 
also indicate arsenical poisoning. — Milk, raw eggs, and 
olive-oil should be administered, and friction and hot 
applications should be applied to the extremities. Hot 
fomentations should be applied to the abdomen after the 
severe symptoms subside. 

5. Strychnia causes sudden and great difficulty in 
breathing, in from fifteen minutes to an hour after a poi- 
sonous do^ has been taken. Twitching of the head and 
limbs is followed by violent convulsions. — An emetic 
should be given and a mixture of camphor and water should 
be administered. 

6. Opium poisoning is indicated by contraction of the 
pupils of the eyes, dizziness, drowsiness, stupor, and insen- 
sibility. The person may be aroused, but quickly relapses 
into stupor. The skin is cold and pale, and not infre- 
quently covered with perspiration. — An emetic should 
be given, and the person must be kept awake by compelling 
him to walk about the room or in the open air, and by 
means of vigorous treatment such as pinching, slapping, 
etc., if necessary. Ammonia should be held to the nos- 
trils. Strong coffee or tea should be administered freely. 
The same treatme7it should accompany poisoning by Mor- 
phine, Laudanum, Paregoric, " Soothing Syrup" and 
"cordials." 

7. Hydrate of Chloral, in overdoses, always produces 
stupor. — An emetic should be administered, and the 
person should be kept awake as in the case of opium 
poisoning. Heat and friction should be applied to the ex- 
tremities. It may become necessary to produce artificial 



EMERGENCIES. 373 

respiration in the same manner as in cases of suffocation 
from drowning, etc. 

8. Oxalic Acid produces a hot acid taste, and burning 
pain in the stomach. Vomiting occurs, and a feeling of 
choking or suffocation is present when this poison has 
been swallowed. — Lime-water, or chalk, lime, or magne- 
sia in water or milk, should be administered freely. If 
lime cannot be otherwise obtained immediately, scrape the 
ceiling and thus obtain a sufficient quantity of it. 

9. Carbolic Acid poisoning should be treated by admin- 
istering half a cupful of olive-oil, or of olive and castor-oil 
combined with chalk, lime, or magnesia. Raw eggs may 
also be given, after all of which an emetic should be em- 
ployed to clear the stomach. Warmth should be applied 
to the extremities. 

10. Phosphorous poisoning should be treated with chalk, 
magnesia, lime, or lime-water. 

11. Poisonous Mushrooms when eaten produce symptoms of 
intoxication, dizziness, and cause objects to appear blue to 
the sight. — An emetic, followed by a dose of castor oil, 
should be employed, and heat applied to the abdomen and 
extremities. 

12. Coal Gas and illuminating gas, when inhaled in suf- 
ficient quantity, produce suffocation. — Doors and windows 
should be thrown open immediately. Artificial respiration 
should be kept up, ammonia applied to the nostrils, and 
mustard poultices to the feet. Warm water and cold water 
alternately dashed on the head and chest serve a good 
purpose. 

13. Drowning. — All clothing should be quickly removed 
from the chest, and the person should then be turned face 
downward, with his forearm under his head in order to 



374 ACADEMIC PHYSIOLOGY. 

free the mouth and nostrils from water, etc. The body- 
should then be laid on its back with the shoulders raised 
on a firm cushion of clothing, etc. The tongue should be 
pulled forward and held by a cloth or band passed over it 
and under the chin. Artificial respiration may then be 
produced in the following manner : Grasp the arms of the 
person above the elbows and draw them horizontally back 
and above his head, keeping them in this position for 
two seconds ; after which turn them down and press them 
firmly against the sides for the same length of time. 
Repeat these movements fifteen to eighteen times per 
minute, and continue them two or three hours if neces- 
sary, for persons have been resuscitated only after long- 
continued efforts. If an assistant is present, he should 
press the lower ribs together, simultaneously with the 
pressing of the person's arms to his sides. The first act 
(raising the arms) induces inspiration, the latter, expira- 
tion. Ammonia or other smelling-salts may be applied to 
the nostrils. As aids to these processes, the limbs should 
be rubbed upwards with hot cloths. Hot and cold water 
may be dashed alternately on the chest. When breathing 
is restored, the person should be placed in a warm bed in 
a well-ventilated room. Artificial respiration may also be 
produced by rolling the body alternately from the back to 
the side, or by raising and depressing the chest, in either 
instance fifteen to eighteen times per minute. 

14. Sunstroke, or Heat Exhaustion. — Remove the person 
to a cool place in the fresh air. Pour cold water upon the 
head, or apply ice to it. Sponge the chest and body with 
cold water. Apply ammonia to the nostrils. 

15. Bleeding from Wounds. — In bleeding from an artery, 
the blood escapes in jets from the wound, corresponding to 



EMERGENCIES. 375 

the impulses of the heart. Pressure must therefore be 
made between the wound and the hea?'t. The pressure must 
be made firmly with fingers and thumbs. Such compres- 
sion may then be supplemented by using a handkerchief 
or other bandage, placing a pad of some kind — a cork, a 
block, or even a stone — upon the artery between the heart 
and the wound, tying the handkerchief firmly over the pad, 
and lastly inserting a stick beneath the handkerchief and 
twisting it so as to press the pad tightly against the lirnb 
or other part, and thus control the bleeding. 

For internal bleedi7ig from the stomach or lungs, the 
person should take a quiet, lying posture, and should be 
given iced drinks, or ice to eat. Bleeding from the nose 
may be stopped by cold applied to the forehead, or to the 
spine, or by syringing the nose with cold alum water. 

16. Burns and Scalds. — Burns and scalds may be treated 
by placing the burnt part in warm water containing car- 
bonate of soda (baking soda). The clothes should be 
carefully removed. The burned parts should be enveloped 
in cloths saturated with equal parts of olive-oil, linseed-oil, 
and lime-water. 

17. Foreign Body in the Throat. —In some instances a for- 
eign body lodged in the throat cannot be expelled by 
coughing ; and when so lodged as to entirely prevent 
breathing, active measures for its removal must be em- 
ployed, in order to save life. Pending the arrival of a phy- 
sician, cause the person, if an adult, to lie face downward 
across a chair (the body and head slanting downward as 
much as possible), and strike the back smartly and, repeatedly 
— in the case of children, while they are being held by the 
legs, head downward. Attempts may be made to reach 
the lodged mass with the fore-finger, hooking it around the 



376 ACADEMIC PHYSIOLOGY. 

obstruction if possible. In ordinary cases, efforts may be 
made to excite vomiting, and consequent expulsion of the 
intruder, by tickling the interior of the throat {fauces) with 
a feather, or other available instrument. 

18. Fainting. — In fainting the circulation of the blood is 
temporarily arrested, or much diminished in force and vol- 
ume, the breathing and functions of the nervous system 
being likewise suspended. Fainting may end in death, 
if too prolonged, or if associated with disease of internal 
organs, especially of the heart. Ordinarily, a person who 
faints from emotion, a close atmosphere, or other passing 
cause, may be readily restored by being laid on the back 
with the head low, selecting a cool place supplied abun- 
dantly with fresh air. All tight articles of clothing should 
be loosened or removed, and a current of cold air, or a 
little cold water, should be directed to the face and chest, 
in order to stimulate respiratory movement. Ammonia 
or aromatic vinegar may be applied to the nostrils for the 
same purpose. Compression of the ribs, and then allowing 
them to expand alternately, as in restoring in suffocation 
from drowning, is effective. " Care should be taken to 
ascertain that there is no obstruction in the throat or air- 
passages, as suffocation from mechanical causes has been 
mistaken for fainting, and the real origin of the mischief 
overlooked, with fatal consequences." 

19. Disinfection. — Disinfection is the destruction of the 
poisons of infectious and contagious diseases. 

Deodorizers, or substances which destroy smells, are 
not necessarily disinfectants, and disinfectants do not 
necessarily have an odor. 

It is extremely important that the people should be in- 
structed with regard to disinfection. They must be taught 



EMERGENCIES. 377 

that no reliance can be placed on disinfectants simply be- 
cause they smell of chlorine or carbolic acid, or possess 
the color of permanganate; and that, in general, proprie- 
tary disinfectants with high-sounding names are practi- 
cally worthless, as they either have no value whatever, or, 
if of value, cost many times as much as they are worth, 
and cannot be used in sufficient quantity. 

Disinfection cannot compensate for want of cleanliness 
or of ventilation. 

/. Disinfectants to be employed. — a. Roll-sulphur (brim- 
stone).; for fumigation. 

b. Sulphate of iron (copperas) dissolved in water in the 
proportion of a pound and a half to the gallon ; for soil, 
sewers, etc. 

c. Sulphate of zinc and common salt, dissolved together 
in water in the proportions of four ounces sulphate and 
two ounces salt to the gallon ; for clothing, bed-linen, etc. 

Note. — Carbolic acid is not included in the above list, for the following 
reasons, — it is very difficult to determine the quality of the commercial arti- 
cle, and the purchaser can never be certain of securing it of proper strength; 
it is expensive when of good quality, and experience has shown that it must 
be employed in comparatively large quantities to be of any use; it is liable 
by its strong odor to give a false sense of security. 

II How to use Disinfectants. — a. In the Sick-Room the 
most available agents are fresh air and cleanliness. The 
clothing, towels, bed-linen, etc., should at once, on removal 
from the patient, be placed in a pail or tub of the zinc 
solution, boiling hot if possible, before removal from the 
room. 

All discharges should either be received in vessels con- 
taining copperas solution, or, when this is impracticable, 
should be immediately covered with copperas solution. 



378 ACADEMIC PHYSIOLOGY. 

All vessels used about the patient should be cleansed with 
the same solution. 

Unnecessary furniture, — especially that which is 
stuffed, — carpets, and hangings, when possible, should 
be removed from the room at the outset ; otherwise, they 
should remain for subsequent fumigation and treatment. 

b. Fumigation with sulphur is the only practicable 
method for disinfecting the house. For this pifrpose the 
rooms to be disinfected must be vacated. Heavy cloth- 
ing, blankets, bedding, and other articles which cannot be 
treated with zinc solution, should be opened, and exposed 
during fumigation, as directed below. Close the rooms as 
tightly as possible; place the sulphur in iron pans sup- 
ported upon bricks ; set it on fire by hot coals, or with 
the aid of a spoonful of alcohol, and allow the room to 
remain closed for twenty-four hours. For a room about 
ten feet square, at least two pounds of sulphur should be 
used ; for larger rooms, proportionally increased quantities. 

c. Premises. — Cellars, yards, stables, gutters, privies, 
cesspools, water-closets, drains, sewers, etc., should be 
frequently and liberally treated with copperas solution. 
The copperas solution is easily prepared by hanging a 
basket containing about sixty pounds of copperas in a 
barrel of water. 

d. Body and Bed Clothing, etc. — It is best to burn all 
articles which have been in contact with persons sick 
with contagious or infectious diseases. Articles too val- 
uable to be destroyed should be treated as follows : — 

Cotton, linens, flannels, blankets, etc., should be treated 
with the boiling-hot zinc solution, introducing piece by 
piece, securing thorough wetting, and boiling for at least 
half an hour. 



EMERGENCIES. 379 

Heavy woollen clothing, silks, furs, stuffed bed-covers, 
beds, and other articles which cannot be treated with the 
zinc solution, should be hung in the room during fumiga- 
tion, pockets being turned inside out, and the whole gar- 
ment thoroughly exposed. Afterward they should be 
hung in the open air, beaten, and shaken. * Pillows, beds, 
stuffed mattresses, upholstered furniture, etc., should be 
cut open, the contents spread out and thoroughly fumi- 
gated. Carpets are best fumigated on the floor, but 
should afterward be removed to the open air, and thor- 
oughly beaten. 

The dead should be thoroughly washed with a zinc solu- 
tion of double strength, wrapped in a sheet wet with the 
zinc solution, and buried at once. 



INDEX. 



Abdomen, muscles of, 57; walls of, 57. 

Absorption by blood-vessels, 102 ; by lym- 
phatics, 80; by villi, 223 ; of oxygen, 113. 

Accommodation of the eye, 323. 

Acid, carbonic, 96, 117, 123, 128; oxalic, 373 ; 
prussic, 215. 

Action of muscles, 51 ; reflex of brain, 242. 

"Adam's Apple," no. 

Adipose {adeps, fat) tissue, 6 ; arrangement of, 
53 ; production of by alcoholic drink, 213. 

Adjustment of the eye, 323. 

Aerial sound-waves, 345. 

■ Air, atmospheric, composition of, 122 ; changes 
in, 123; foreign matter in, 125; in lungs, 
115 ; in-door air, its pollution, 128; of ele- 
vated regions, 120; pressure of, on tym- 
panic membrane of ear, 341 ; quantity for 
respiration, 117, 135. 

Air-cells of lungs, in. 

Air-passages, 109-111. 

Albumen {albus, white), 4, 146. 

Alcohol, how produced, 187; nature of, 190; 
uses of, 190 ; poisonous properties of, 191. 

Alcoholic beverages, 187; effects or! blood 
and circulation, 102; on blood-vessels, 
103; on digestion, 192, 212; on the lungs 
and respiration, 140; on the muscles, 71 ; 
on nervous system, brain, etc., 262 ; tend 
to insanity, 264; to blunt moral sense, 
265; lead to crime, 265; impair the will, 
263; weaken muscles, 71. 

Alkalies, as antidotes to acid poisons, 371 ; as 
poisons, 371. 

Ammonia, 125, 372, 374. 

Amputation, 250 {note). 

Anatomy defined, 2. 

Aneurism, 102. 

Animal food, 158; heat, 98. 

Ankle, 32, 61. 

Antagonist muscles, 48, 59. 

Aorta, 85, 91. 

Appetite, 193 ; narcotic, 191, 215, 264. 

Aqueous humor, 320. 

Arms, bones of, 27 ; muscles of, 58. 

Arsenic, poisoning by, 371. 

Arteries, 91 ; functions and structure of, 93. 

Arterial circulation, 86, 93. 

Asphyxia, 118, 373. 

Atlas vertebra, 24. 

Atmosphere, 122. 

Auditory canal, 338; nerve, 339, 343, 347. 

Auricles (Lat. aures, ear) of the heart, 83. 

Axis vertebra, 24. 



Bacilli (i.e., a little stick), 127. 

Bacon as food, 163. 

Barley as food, 153. 

Bathing,' 288. 

Baths, kinds, effects of, and rules for, 288-295, 

Beans as food, 154. 

Beer, 188, 214. 

Beets as food, 155. 

Biceps muscle, 58. 

Bicuspid teeth, 19. 

Bile, 220. 

Black-heads (skin-worms), 279. 

Bleeding from arteries, 94, 374; from lungs 
375; from nose, 375; from stomach, 375: 
from veins, 94. 

Blind-spot of eye, 324. 

Blindness, 315. 

Blisters, 276. 

Blood, amount of, 79 
composition of, 76 

from digestion, 76; from respiration, 82, 
86, 113; from alcoholic drink, 102; from 
heat ; temperature of, and how regulated, 
98 ; varying color of, 76. 

Blood-vessels, 80, 91-97. 

Body, composition of, 4; divisions of, 16; tis- 
sues of, 6. 

Boiling of food, 170. 

Bone, composition of, 1 
n ; structure of, 12 ; 
compression, etc., 3 
42 ; repair of, 12, 42 

Brain, divisions of, 235 
238 ; disease of, 261 

tasking, 255; size of, 234 ; functions of, 
237; hygiene of, and effects of narcotics 
on, 253-266. 

Brandy, 189. 

Bread, as food, 150; baking of, 172; mixing 
of, 171. 

Breathing, 113; costal and diaphragmatic, 
118; insufficient, 119; mouth-breathing, 
126, 305 ; oppression of, in elevated re- 
gions, 120 ; organs of, 108. 
Breast-bone (sternum), 25. 

Bronchial tubes, in. 

Burns, 283, 375. 
Bursae, 50. 

Cabbage as food, 156. 
Calcium, 4. 

Canals, alimentary, 194 ; Haversian, 12 ; semi- 
circular of ear, 345 ; spinal, 23. 



circulation of, 80 ; 
changes arising in, 



; at different ages, 
deformities of, from 
; fractures of, 12, 
hygiene of, 37~43- 
structure of, 233- 
injuries, 238 ; over- 



381 



382 



INDEX. 



Canine teeth, 19. 

Canned food, 157. 

Capillaries, 79, 94, 277. 

Carbon, 4, 147. 

Carbonaceous elements, 4. 

Carbonic acid gas, effect on blood, 118; excess 
in air, 118, 123 ; exhaled from lungs, etc., 
117, 128 ; proportion in pure air, 116, 123. 

Carbonic oxide, 124 (note 2). 

Carbonate of lime, 4. 

Cardiac impulse, 88. 

Carpal bones, 28. 

Cartilage, 13, 23, 24, 35. 

Cartilaginous, tissue, 6. 

Carrots as food, 155. 

Casein, 146, 167. 

Cauda equina, 248. 

Cell structure of tissues, 5. 

Cement of teeth, 20. 

Cerebellum, 235, 238. 

Cerebrum, 235. 

Cess-pools, 137. 

Cheese as food, 167. 

Chest, 24; contents of, 25; form of, 25 ; de- 
formity of, 39; development of, 39, 68, 

Chloral-hydrate, nature and effects of, 264; 
poisoning by, 372. 

Chocolate, 186. 

Choroid coat of eye, 319. 

Chyle, 222. 

Chyme, 208. 

Cider, 188. 

Cilia, no. 

Cigarette-smoking, 140, 298, 365. 

Circulation of blood, 80; organs, of, 81, 91; 
rapidity of, 88; retarded by improper 
clothing, 70, 100; effects of exercise on, 
63, 101 ; effects of alcohol, tobacco, and 
other narcotics on, 102 ; general hygiene 
of, 100-105. 

Cisterns, construction and water of, 176. 

Clavicle (shoulder-blade), 26. 

Classification of foods, 144. 

Clot, blood, 76. 

Clothing, functions of, 298; color of, 303 ; im- 
proper character of, 38, 69, 101, 304; ma- 
terials and values of, 300-303 ; hygiene of, 
298-309. 

Coagulation of blood, 76, 103. 

Coffee as a beverage, 185. 

Coccyx, 21, 22. 

Cochlea, 344. 

Cold and respiration, 117. 

Color, sense of, 326 ; value of, in clothing, 303. 

Color-blindness, 327. 

Combustion, 63, 98. 

Condiments, 172. 

Confectionery, adulteration of, 157. 

Congestion, 98, 140, 211. 

Connective tissue, 6, 273. 

Consumption, 129, 261. 

Cooking, methods of, 169-174. 

Cord, spinal, 23, 241 ; vocal, 109, 364. 

Cornea of the eye, 318, 323, 325. 

Corpuscles of blood, 75, 77 ; tactile, 278, 360. 

Costal cartilages, 24, 35; muscles, 57, 70, 114. 



Cotton as clothing material, 302. 

Cranial nerves, 245. 

Crime related to alcoholic drink, 265. 

Crossing of nervous impulses, 243. 

Curvature of spine, 38, 70. 

Cuticle, 272. 

Crystalline lens, 320. 

Daily waste, 5, 63, 76, 143. 

Deafness, 350. 

Decomposition, 137, 160, 163, 168. 

Deformities, 11, 38, 70. 

Deglutition, 202. 

Deltoid muscle, 58. 

Delirium, 263. 

Delusion of the senses, 263, 329. 

Dentine, 19. 

Derma, 273. 

Diaphragm, 57, 114, 118, 195. 

Diastole, 87. 

Diet, 149; mixed, 150; variety in, 150; re- 
quisites of, 151. 

Digestion, 193 ; salivary, 198-202 ; gastric, 
205-207 ; intestinal, 216; time of, 209 ; cir- 
cumstances effecting, 209 ; alcohol, to- 
bacco, and digestion, 211-216; general 
hygiene of, 197, 198,200, 201,209, 211- 
216. 

Disinfection, 127, 140, 376. 

Dissection, 2. 

Dislocations, 27, 31, 41. 

Distilled liquors, 188. 

Drainage, 136-140. 

Drain-diseases, 136-140. 

Drinks, artificial, 184; natural, 174; alco- 
holic. 187. 

Drowning, resuscitation from, 373. 

Drum of ear, 339. 

Duct, bile, 206, 220; lachrymal, 316, 321; 
nasal, 321; thoracic, 80. 

Duodenum, 204, 206, 208, 217. 

Dura mater, 235. 

Dyspepsia, 151, 162, 186, 192, 213. 

Ear, divisions of, 336; structure of, 336-345 ; 
foreign bodies in, 349; hygiene of, 347- 

35'- 
Ear-wax, 338, 348. 

Eating, manner of, 197 ; excess in, 151, 214. 
Effects of stimulants and narcotics, 71, 89, 

102, 140, 184, 191, 201, 211-216, 259, 262- 

266, 297, 334, 35', 365- 
Efferent nerves, 244; impulses, 244, 250. 
Eggs as food, 168. 
Elasticity of arteries, 93; of bones, 11; of 

cartilages, 13, 23 ; of lungs, in, 115. 
Elbow, 27. 
Elements of air, 116, 123; of the body, 4; 

of food, 4, 145-149. 
Emotions, 253, 271, 376. 
Enamel, of teeth, 19. 
Energy supplied by food, 143. 
Epidermis, 272, 274, 288. 
Epithelial tissue, 6. 
Epiglottis, no, 202. 
Ether, 322. 



INDEX. 



383 



Eustachian tube, 339, 341, 35 1 5 closure of 

and effects, 350. 
Evaporation, 284, 285, 297. 
Excretion, 5, 108, 117, 125, 223, 271, 289. 
Exhalation from decaying matter, 136; from 

drains, 137-139 i rrom lungs, 108, 113, 116, 

125; from sewers, 138. 
Exercise of brain, 254; of bones, 37; of 

muscles, 62 ; of senses, 328, 357-358, 363 • 
Expiration, 108, 115. 
Expired air, nature of, 116. 
Expression, muscles of, 54. 
Extremities, upper, 26, 58 ; lower, 30, 60. 
Eyes, 314; care of, 320-336; muscles of, 316; 

nerves of, 319, 323; foreign bodies in, 

333 ; hygiene of, 320-336. 
Eye-teeth (canine) 19, 197. 

Face, bones of, 17; muscles of, 53; washing 
of, 295. 

Fainting, 118, 376. 

Far-sight, 325. 

Fasciculi, 48. 

Fat, cells of, 6; value as food, 146. 

Fatigue, 64, 186, 255. 

Felon, 12, 40. , 

Femur (thigh-bone), 30. 

Fenestra ovalis, 344; rotunda, 344. 

Fermentation, 171, 187. 

Fermented liquors, 188. 

Fever, 177, 

Fibres of muscles, 48 ; of nerves, 244. 

Fibrine, 4, 77, 146. 

Fibrous tissue, 6, 235, 273. 

Fibula, 31. 

Filters and nitration, 181. 

Filth, danger of, 8, 136. 

Fire-place ventilation, 129, 134. 

Fish as food, 163. 

Flavors, perception of, 354, 

Flexor muscles, 61. 

Fluids of body, 6. 

Food, articles of, 152-168; necessity of, 5, 
143; elements required in, 5,145; quan- 
tity necessary, 151 ; digestion of, 193-225 ; 
oxidation of, in digestion, 140-147 ; varie- 
ties of , 145; preparation of, 169. 

Food-stuffs classified, 144. 

Food, bones of, etc., 32, 61. 

Fore-arm, bones of, 27 ; muscles of, 58. 

Foreign body in throat, 375 ; eye, 333 ; ear, 

^ 349 " , , 

Fractures of bones, 14, 41. 

Freezing of water, 182. 

Friction of the skin, 289, 290, 294. 

Friction-bath, 294. 

Fruits as food, 156. 

Frying of food, 170. 



Ganglia, 90, 250, 252. 

Gases, diffusion of, 116; poisonous, 117, 1 
128 ; proportions of, in atmosphere, 1 
123 ; drain and sewer gases, 138. 

Gastric juice, 205. 

Gelatine, 4, 11, 173. 

General anaemia (bloodlessness), 224. 

General sensations, 314. 



Gin, 189. 

Glands, lachrymal, 316-321; salivary, 199; 
sabaceous, 277, 278 ; sweat, 277, 279; gas- 
tric, 205. 

Glasses for eye-sight, 334. 

Glottis, no, 202. 

Gluten, 146, 152. 

Grain, 152. 

Gray matter of brain, 233 ; of nerves, 242, 244. 

Gustatory {gusto, I taste) nerve, 354 {note). 

Gymnastics, 65, 260. 

Hair, structure, functions and care of, 286, 

296. 
Haemoglobin (literally, blood-sphere), 79 

{note). 
Hands, 28, 297. 
Hardness of water, 179. 
Head, bones of, 17. 
Hearing, sense of, 336 ; mechanism of, 336- 

345; care of, 347-352; dangers to, 349; 

effects of narcotics on, 351. 
Heart, 81-84; functions of, 81; rapidity of 

contraction of, 88, 104 ; sounds of, 88 ; 

structure of, 82 ; labor of, 87, 104; disease 

of, 89, 104 ; effects of narcotics on, 103 ; 

hygiene of, 101-104. 
Heat, effect of, on blood, 284 ; dry heat, 285 ; 

moist heat, 286. 
Hemispheres of brain, 235. 
Hinge-joints, 34. 
Hip-joint, 31. 
Humerus, 27. 
Humors of eye, 320, 330. 
Hunger, 5, 63, 143. 
Hydrogen, 4. 
Hygiene defined, 3; personal, 8. 

Ice-water, 183. 

Illusions, 329, 355, 362. 

Impressions, retinal, corrected by sense of 
touch, 328. 

Impulses, nervous, conduction of, 244, 252. 

Impure air, effects of, 117, 122, 125, 135; im- 
pure water, 175-179. 

Incisor teeth, 17. 

Indian meal as food, 153. 

Injury to bones and joints, 41 ; to medulla 
oblongata, result of, 240; to spinal cord, 
24, 242, 243. 

Inherited disease, 261. 

Insalivation, 198. 

Insanity, 261, 262. 

Intestines, 194, 216. 

Inspiration, 108, 114, 116. 

Intoxication, 262. 

Intercostal muscles, 57, 114, 118. 

Involuntary muscles, 47. 

Inverted retinal image, 323. 

Iris, 319. 

Irritability, nervous, 249; muscular, 51. 

Irritation of cut ends of nerves, 250. 

Jaws, movement of, 20, 197. 

Joints, uses, structure, and kinds, 33. 

Judgment combined with sensation, 327, 357. 

Juice of fruits, 156; gastric, 205; intestinal, 
220; pancreatic, 221. 



3^4 



INDEX. 



Kidneys, functions of, 143, 282 ; relations to 

skin and lungs, 282. 
Knee-joint, 32. 
Knee-pan (patella), 32. 
Knock-knees, 41. 

Labyrinth of ear, 343. 

Lachrymal duct and gland, 321. 

Lacteals, 219, 223. 

Larynx, 109, 364. 

Lead-poisoning, 180. 

Leather made from skin, 273. 

Leg, bones of, 31 ; muscles, 60. 

Lens, crystalline, 320, 323, 325, 330. 

Levers, bones as, 62. 

Ligaments, 14, 31, 32, 33, 36. 

Light, direction of, 331. 

Lime in bones, n. 

Linen as clothing material, 302. 

Liver, 209, 220. 

Losses of the blood, 76, 107. 

Lungs, blood-vessels of, 113; absorption of 
oxygen by, 113; excretion by, 113; cells 
of, 113; capacity of, 116; sounds of, 119; 
effects of narcotics on, 140 ; general hy- 
giene of, 117, 119, 122-140. 

Lymph, 79 ; lymphatics, 80. 

Marrow of bones, 13; spinal marrow, 23, 

241. 
Mastication, importance of, 42, 197. 
Malaria, 177. 
Malt, 188. 
Meat, values as food, 158-163 ; unfit for use, 

kinds of, 160; special properties, 161. 
Medulla oblongata, 240; functions of, 240. 
Membrane, mucous, m, 194,356; synovial, 

35- 

Milk as food, 164; care of, 166; disease from, 
166; adulteration of, 165. 

Mind, faculties of, 252; health of, 253-266; 
impairment of faculties, 254-259, 262. 

Mitral valves, 83. 

Moisture in air, 117, 123. 

Molar teeth, 19, 197. 

Morphia, poisoning by, 372. 

Motor nerves, 242, 244. 

Murmurs, respirator)', 120. 

Muscles, number and uses, 47, 48; classes of, 
47; mode of attachment, 49; blood and 
nerve supply of, 63; contractility of, 51, 
52; development and over-development 
of, 65 ; exercise of, proper and improper, 
65 ; forms of exercise, 67 ; feats of strength, 
65 ; inactivity of, 64 ; gymnastics, 65 ; rest 
of, 64; effects of narcotics on, 71, 104; 
general hygiene of, 62-72. 

Muscular tissue, 6. 

Mushrooms, poisoning by, 373. 

Mutton as food, 162. 

Myopia (near-sight), 325. 

Nails, 287. 

Narcotics, 71, 89, 102-105, 140, 184-192, 201, 

211-215, 259, 262-267, 297, 3Si, 365. 
Narcotic sleep, 259. 
Nasal bones, 17, 18; cavities, 17, 356. 



Near-sight, 325. 

Nerves, functions of, 244; structure of, 233, 
244; afferent or sensory, 244; efferent or 
motor, 244; effects of irritation of cut 
ends of, 250 ; tissue of the, 233 ; rapidity 
of impulse, 252 ; effects of narcotics on 
the, 259, 262-266; general hygiene of the, 
253-267. 

Nervous system, cerebro-spinal, 232 ; divisions 
of, 232; functions of, 232-250; exercise, 
rest, and recreation of, 253-261 ; effects 
of narcotics on, 259, 260, 262-267; gen- 
eral hygiene of, 253-267. 

Nervous tissue, 6, 233. 

Neuralgia, 251. 

Nicotine, 215, 266. 

Nitrogen of air, 116, 123. 

Nitrogenous food, 4, 145. 

Nose, 6, 17; breathing through the, 126; or- 
gan of smell, 356. 

Nucleated cells, 5. 

Nucleus, 5. 

Nutrition, 143; effected by circulation of the 
blood, 76, 80; foods and their values, 152- 
169; preparation of food, 169; requisites 
for, 149-152; beverages, 174-192; alcohol 
and, 192, 211; general hygiene of, 143- 
192. 

Oatmeal as food, 153. 

Objects, visual images of, 321, 326, 327-329. 

Odontoid peg, 24. 

Odors, 357-359- 

OZsophagus, 194, 203. 

Oil-glands, 278. 

Olfactory nerves, 356. 

Opium, nature and effects of, 259; poisoning 
by, 372. 

Optic nerve, 247, 318, 323. 

Organ defined, 6. 

Organic matter in expired air, 125; in drink- 
ing-water, 137, 175. 

Osseous system, 11. 

Out-door exercise, 66, 261. 

Over-exercise of muscles, 65; of brain, 255; 
of eyesight, 332. 

Oxalic acid, poisoning by, 373. 

Oxidation, in tissues, 63, 98, 140, 147. 

Oxygen, nature of, 123 ; necessity of, 107, 
117, 128; proportion of in air, 116, 123 ; 
oxygen starvation, 107, 117, 128. 

Oysters as food, 164. 

Ozone, 125. 

Pain, sensation of, 360, 361. 

Pancreas (J>an, all ; kreas, flesh), 221. 

Palate, 120, 202. 

Palpitation of heart, 104. 

Papils, 274, 353, 360. 

Paralysis, 71, 237, 262, 263. 

Parotid glands, 199. 

Parsnips as food, 155. 

Patella (knee-cap), 32. 

Peas as food, 154. 

Pericardium, 82. 

Peristaltic motion, 53. 

Periosteum, 12. 



INDEX. 



385 



Peritoneum, 196. 

Perspiration, amount of, 280; constituents of, 
280; functions of, 271, 283 ; effects of heat 
on, 283; sensible and insensible, 281. 

Pharynx, no, 202. 

Phosphate of lime, 4. 

Phosphorus, poisoning by, 373 ; as an ele- 
ment, 4. 

Physiology defined, 2. 

Pia mater, 234. 

Pigment cells, 275, 319. 

Pivot-joint, 34. 

Plasma, 75. 

Pleura, 112. 

Pneumogastric nerve, go. 

Poisoning, antidotes in, 371. 

Poisonous clothing, 309. 

Pons Varolii, 240. 

Pores of skin, 279. 

Pork as food, 162. 

Posture of body, 38, 69. 

Potatoes as food, 147, 154. 

Poultry as food, 163. 

Proteids, 145. 

Protoplasm (i.e., first formed), 5, 75. 

Pulp of teeth, 19. 

Pulmonary arteries, 85, 86; circulation, 86; 
veins, 86. 

Pulse, rapidity of, 88. 

Pumpkins as food, 156. 

Pupil of eye, 319. 

Purity of air, 117, 122, 128; water, 174-183. 

Pylorus, 204, 208. 

Quality of sound, 346 ; pitch of, 346, 364. 
Quantity of blood in body, 79 ; distribution of, 
to parts, 79. 

Radius, 27. 

Rain-water, 175. 

Reaction after cold bath, 292. 

Recreation, 260. 

Reflex action, 242. 

Respiration, 107 ; artificial, 374 ; organs of, 
108; process of, 113; kinds of, 118; 
movements of, 1 14 ; changes in air during, 
116; residual, tidal, and complemental 
air in, 115; improper or insufficient, 119; 
exercise and, 66; elevated regions and, 
120; rapidity of, 117; quantity of air 
required in, 117; influence of narcotics 
on organs of, 140; general hygiene of, 
117-121, 122-140. 

Respiratory centre in medulla oblongata, 240. 

Repair and waste, 5, 63, 80, 143. 

Repair of broken bone, 14, 42. 

Rest of brain, 255, 260; rest of muscles, 64; 
of eyes, 332 ; in sleep, 255. 

Rete Malpighii, 275. 

Retina, 319, 323, 324,325- 

Regulation of bodily temperature, 98, 283, 
297,299. 

Ribs, 24, 39- 

Rice as food, 153. 

Rickets, 12, 41. 

Rivers, pollution of water of, 176, properties 
of water of, 175-180. 

Roasting of meats, 170. 



Roots of nerves, 248. 
Rowing as exercise, 68. 
Rum, 189. 

Running as exercise, 68. 
Rye as food, 152. 

Sacrum, 20, 21. 

Saliva, 200 ; amount of, 200 ; functions of, 200. 

Salivary glands, 199. 

Salt, importance of, 149. 

Salt meat as food, 163. 

Scalp, care of, 296. 

Scapula (shoulder-blade), 26. 

Scars, 275 (note), 276. 

Sciatic nerve, 248. 

Sea-bathing, 293. 

Secretion of bile, 220; of saliva, 199; of tears, 
316, 321 ; of gastric juice, 205 ; of perspira- 
tion, 280; of sebaceous matter, 278; of 
mucus, 273, 356; of ear-wax, 338; of 
synovial fluid, 35. 

Semilunar valves, 85, 93. 

Sensation, divisions of, 314; of hearing, 336; 
of sight, 315 ; of smell, 355 ; of taste, 352 ; 
of touch, 359; of pain, 359. 

Senses, special, 314; complementary, 328, 
352 ; deception by, 329, 353, 362 ; subject 
to the judgment, 353 ; education of, 357, 

o 363- 

Sensor}' or afferent nerves, 244. 

Sewers, 138. 

Sewer-gas, danger of, 138 ; protection against, 
139- 

Shoes and boots, improper, 307. 

Shortness of breath, 39, 119. 

Sight, sense of, 314; care of, 330; curiosities 
of, 324-327. 

Silk as clothing material, 302. 

Skeleton, 15; divisions of, 16; functions of, 
15 ; structure of, 16-36. 

Skin, 271 ; absorption by, 281 ; excretion by, 
280; necessity for cleanliness of, 279, 
288 ; respiration through, 282 ; regulative 
agency of, 99; structure of, 275-280; hy- 
giene of, 288-309. 

Skull, bones of, 17. 

Sleep, amount required at different ages, 258 ; 
functions of, 258 ; time for, 258 ; sound- 
ness of, 259. 

Smell, sense of, 355; curiosities of, 357; im- 
perfection of, 359; function of, 355; organ 
of, 356; hygiene of, 357. 366. 

Soap, impurities in, 291 ; use of, 291, 295. 

Solar plexus, 251. 

Sound, 345. 

Sounds of heart, 88; of respiration, 119. 

Speech, organs of, 109. 

Spinal canal, 23 ; cord, 23, 241 ; curvature, 
38 ; nerves, 248. 

Spinal column, 21. 

Spleen, 221. 

Sprains, 41. 

Springs and water of, 177. 

Starch, digestion of, 200. 

Sternum, 25. 

Stomach, 203 ; digestion in, 207; movements 
of, 208 ; structure of, 203 ; effects of alco- 
hol, tobacco, etc., on, 211-215. 



386 



INDEX. 



Straining the eyes, 331 ; the muscles, 65. 

Strength, muscular, 64, 66. 

Study of Anatomy, Physiology, and Hygiene, 

objects of the, 1. 
Strychnia, poisoning by, 372. 
Suffocation, resuscitation from, 374, 375. 
Sugar as food, 147 ; as source of alcohol, 187. 
Sunstroke, treatment of, 374. 
Surface-water, 176. 
Sutures, 17, 35. 
Swallowing, 202. 
Sweat-glands, 279. 
Swimming as exercise, 68. 
Sympathetic nervous system, 232, 250. 
Synovial fluid, 35; membrane, 35. 
System defined, 7. 
Systole, 87. 



Tactile (L. tango, I touch) corpuscles, 278, 
360. 

Taste, sense of, 352 ; complexity of, 352 ; curi- 
osities of, 354 ; organ of, 353 ; uses of, 352. 

Tea as a beverage, effects of, 184. 

Tears, 321. 

Teeth, classes, functions, 17; care of, 42. 

Temperature of blood, 98 ; regulation of, 98, 
283, 299. 

Temperature, sense of, 362. 

Tendon of Achilles, 50. 

Tendons (tendo, I stretch), 50. 

Thirst, nature of, 5, 144; alcoholic, 191. 

Thoracic duct, 80, 220. 

Thorax (chest), 24 ; distortion of, by tight 
clothing, 39; natural form of, 25. 

Tibia, or shin-bone, 31. 

Tight-clothing, effects of, 39, 70, 306. 

Tobacco, nature of, 215 ; effects of the use of, 
71, 104, 140, 201, 215, 266, 351, 365. 

Tongue, 194, 196, 353. 

Touch, sense of, 359; curiosities of, 361 ; or- 
gan of, 360 ; impressions off 362 ; educa- 
tion of, 363. 

Trachea (wind-pipe), no. 

Trichina spiralis, 162. 

Tri-cuspid {tres, three; and citspis, a point) 
valve, 83. 

Trunk of body, 20 ; cavities of, 57 ; bones of, 
20. 

Turbinal {turbo, I turn) bones, 18. 

Tympanum of ear, 339. 



Ulna, 27. 

Uncleanliness of clothing, 307; of person, 

289; of surroundings, 136. 
Unstriated muscles, 52. 
Unwholesome air, 117, 125, 127; food, 159- 

168; water, 175-183. 
Unripe fruit, 157; canned, 157. 



Valves of arteries, 85, 93 ; of heart, 83 ; of 
stomach, 203 ; of veins, 96. 

Varnish, result of covering the skin with, 283 
(note). 

Vaso-motor nerves, 98. 

Veal as food, 161. 

Vegetable foods, articles and values cf, 146 

__ . 1 52-i57- 

Veins, 96. 

Velocity of muscular contraction, 52. 

Vena cavae (i.e., empty veins), 97. 

Venous blood, 95, 96. 

Ventilation, 128; artificial, 135; natural, 131; 
means and methods of, 130-135; neces- 
sity of, 128. 

Ventricles (ventriculus, a little belly), of 
heart, 83. 

Vertebrae, 21-23. 

Vestibule, 343. 

Vibrations of sonorous bodies, 343 ; of tym- 
panic membrane, 346; of vocal cords, 
109, 364. 

Villi (i.e., shaggy hair), 219. 

Vinegar, use as an acid, 201, 370; influence on 
digestion, 201. 

Vision, conditions essential to perfect, 330. 

Vitreous (vitrum, glass) humor, 320. 

Vocal cords, 109, 364. 

Voice, 109, 364. 

Voluntary muscles, 47. 

Vomer, 18. 

Walking as exercise, 68. 

Water, amount of, in body, 4; aeration of, 

182 ; boiling of, 182 ; care of sources, 

175; freezing of, 182; filtration, 181; 

hardness, 179; pollution of, 139, 175-181; 

varieties of, 175 ; germs of disease in, 137, 

176-179. 
Water-proof clothing, 303. 
Waste from bodily action, 5, 37, 63, 107, 125, 

I43-. 
Waste-pipes, sealing of, 137-139. 
Waste products, 5, 37, 63, 107, 125, 213, 223, 

281. 
Weight of brain, 234. 
Wheat as food, 152. 
Whiskey, 189. 

White nervous tissue, 233, 235, 242. 
Wind-pipe, no, 202. 
Wines, 188, 189. 
Wisdom teeth, 19. 
Woollen clothing, 301. 
Work and rest, 254, 255, 260. 
Wounds, compression of, in bleeding from, 

94, 374- 
Wrist, 28. 

" Yellow-spot " of eye, 324. 
Youth, bones of, 11. 



LIBRARY OF 




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